<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with Wdesk from Workiva-->
<!--Copyright 2023 Workiva-->
<!--r:89dc5c6a-b628-4a54-9516-63176f8887b3,g:c9edc826-fa81-4bea-a764-71bdcdc114d1-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
  <link:roleRef roleURI="http://pwp.com/role/CoverPage" xlink:type="simple" xlink:href="pwp-20221231.xsd#CoverPage"/>
  <link:definitionLink xlink:role="http://pwp.com/role/CoverPage" xlink:type="extended" id="ie99428a5834e4eab9ad78a34ebc30d2c_CoverPage">
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentInformationLineItems_364f94a0-daee-468d-a0cd-68ecc1b034bd" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_DocumentInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentType_4009ab03-254a-46de-9d9a-b908b2b1cc6d" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_DocumentType"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_364f94a0-daee-468d-a0cd-68ecc1b034bd" xlink:to="loc_dei_DocumentType_4009ab03-254a-46de-9d9a-b908b2b1cc6d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentAnnualReport_07b24000-29e7-47a8-861c-678c8b325324" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_DocumentAnnualReport"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_364f94a0-daee-468d-a0cd-68ecc1b034bd" xlink:to="loc_dei_DocumentAnnualReport_07b24000-29e7-47a8-861c-678c8b325324" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentPeriodEndDate_50c59a68-7d9e-433f-bf0f-869e33a71349" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_DocumentPeriodEndDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_364f94a0-daee-468d-a0cd-68ecc1b034bd" xlink:to="loc_dei_DocumentPeriodEndDate_50c59a68-7d9e-433f-bf0f-869e33a71349" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_CurrentFiscalYearEndDate_52336bc0-452b-4fad-bd6d-4e8d35f7631c" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_CurrentFiscalYearEndDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_364f94a0-daee-468d-a0cd-68ecc1b034bd" xlink:to="loc_dei_CurrentFiscalYearEndDate_52336bc0-452b-4fad-bd6d-4e8d35f7631c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentTransitionReport_ee8856ce-c462-4668-a1c6-436b71cab247" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_DocumentTransitionReport"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_364f94a0-daee-468d-a0cd-68ecc1b034bd" xlink:to="loc_dei_DocumentTransitionReport_ee8856ce-c462-4668-a1c6-436b71cab247" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityFileNumber_ab61a73f-40d0-4879-8640-7b7e8571ac39" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityFileNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_364f94a0-daee-468d-a0cd-68ecc1b034bd" xlink:to="loc_dei_EntityFileNumber_ab61a73f-40d0-4879-8640-7b7e8571ac39" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityRegistrantName_0dacd78a-9818-4d83-9482-8654cf13ad53" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityRegistrantName"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_364f94a0-daee-468d-a0cd-68ecc1b034bd" xlink:to="loc_dei_EntityRegistrantName_0dacd78a-9818-4d83-9482-8654cf13ad53" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityIncorporationStateCountryCode_10d4967a-773b-41bc-a72a-ccd6ed4dc94a" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityIncorporationStateCountryCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_364f94a0-daee-468d-a0cd-68ecc1b034bd" xlink:to="loc_dei_EntityIncorporationStateCountryCode_10d4967a-773b-41bc-a72a-ccd6ed4dc94a" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityTaxIdentificationNumber_5a07d6af-425b-4b7e-a640-1e050290ee9e" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityTaxIdentificationNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_364f94a0-daee-468d-a0cd-68ecc1b034bd" xlink:to="loc_dei_EntityTaxIdentificationNumber_5a07d6af-425b-4b7e-a640-1e050290ee9e" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressAddressLine1_edb13823-cf99-4bb3-9875-a6cc2b1c297c" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityAddressAddressLine1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_364f94a0-daee-468d-a0cd-68ecc1b034bd" xlink:to="loc_dei_EntityAddressAddressLine1_edb13823-cf99-4bb3-9875-a6cc2b1c297c" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressCityOrTown_62b2646a-56e5-412a-aab6-a6433ebfa1dd" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityAddressCityOrTown"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_364f94a0-daee-468d-a0cd-68ecc1b034bd" xlink:to="loc_dei_EntityAddressCityOrTown_62b2646a-56e5-412a-aab6-a6433ebfa1dd" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressStateOrProvince_14976f3c-fc08-4d6c-8159-bde67fcf58c2" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityAddressStateOrProvince"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_364f94a0-daee-468d-a0cd-68ecc1b034bd" xlink:to="loc_dei_EntityAddressStateOrProvince_14976f3c-fc08-4d6c-8159-bde67fcf58c2" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressPostalZipCode_40bcb3dc-5087-4e7f-b41e-b21955682f1d" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityAddressPostalZipCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_364f94a0-daee-468d-a0cd-68ecc1b034bd" xlink:to="loc_dei_EntityAddressPostalZipCode_40bcb3dc-5087-4e7f-b41e-b21955682f1d" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_CityAreaCode_0ffd3495-8178-4256-8554-2b3f03aad62a" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_CityAreaCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_364f94a0-daee-468d-a0cd-68ecc1b034bd" xlink:to="loc_dei_CityAreaCode_0ffd3495-8178-4256-8554-2b3f03aad62a" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LocalPhoneNumber_3ed05852-f542-4a77-9fd9-0d74eb5642e9" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_LocalPhoneNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_364f94a0-daee-468d-a0cd-68ecc1b034bd" xlink:to="loc_dei_LocalPhoneNumber_3ed05852-f542-4a77-9fd9-0d74eb5642e9" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_Security12bTitle_3e61bd7f-3188-4490-8f74-cdd40bceecb8" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_Security12bTitle"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_364f94a0-daee-468d-a0cd-68ecc1b034bd" xlink:to="loc_dei_Security12bTitle_3e61bd7f-3188-4490-8f74-cdd40bceecb8" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_TradingSymbol_cf1a5836-7f67-4762-bb6b-bd90a70643e8" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_TradingSymbol"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_364f94a0-daee-468d-a0cd-68ecc1b034bd" xlink:to="loc_dei_TradingSymbol_cf1a5836-7f67-4762-bb6b-bd90a70643e8" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_SecurityExchangeName_94e1fdb0-ff04-4ec4-a9aa-f8fe2e993447" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_SecurityExchangeName"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_364f94a0-daee-468d-a0cd-68ecc1b034bd" xlink:to="loc_dei_SecurityExchangeName_94e1fdb0-ff04-4ec4-a9aa-f8fe2e993447" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityWellKnownSeasonedIssuer_5a91a3ed-7f75-48c8-93a0-c7f22f4f43d4" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityWellKnownSeasonedIssuer"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_364f94a0-daee-468d-a0cd-68ecc1b034bd" xlink:to="loc_dei_EntityWellKnownSeasonedIssuer_5a91a3ed-7f75-48c8-93a0-c7f22f4f43d4" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityVoluntaryFilers_111b5cda-a158-43e8-84fb-a24089f09ad7" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityVoluntaryFilers"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_364f94a0-daee-468d-a0cd-68ecc1b034bd" xlink:to="loc_dei_EntityVoluntaryFilers_111b5cda-a158-43e8-84fb-a24089f09ad7" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCurrentReportingStatus_71bc338b-5c1f-42d1-afe8-3c7414842446" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityCurrentReportingStatus"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_364f94a0-daee-468d-a0cd-68ecc1b034bd" xlink:to="loc_dei_EntityCurrentReportingStatus_71bc338b-5c1f-42d1-afe8-3c7414842446" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityInteractiveDataCurrent_46ac194c-c6ec-4c92-a280-5b3543ddcc38" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityInteractiveDataCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_364f94a0-daee-468d-a0cd-68ecc1b034bd" xlink:to="loc_dei_EntityInteractiveDataCurrent_46ac194c-c6ec-4c92-a280-5b3543ddcc38" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityFilerCategory_f7ef3265-b1af-4a3d-bda4-b93254977741" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityFilerCategory"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_364f94a0-daee-468d-a0cd-68ecc1b034bd" xlink:to="loc_dei_EntityFilerCategory_f7ef3265-b1af-4a3d-bda4-b93254977741" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntitySmallBusiness_f80e3bb0-105a-48de-a707-f4e21d949b0f" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntitySmallBusiness"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_364f94a0-daee-468d-a0cd-68ecc1b034bd" xlink:to="loc_dei_EntitySmallBusiness_f80e3bb0-105a-48de-a707-f4e21d949b0f" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityEmergingGrowthCompany_321f0e2c-3d1b-4d53-8270-231c32754954" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityEmergingGrowthCompany"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_364f94a0-daee-468d-a0cd-68ecc1b034bd" xlink:to="loc_dei_EntityEmergingGrowthCompany_321f0e2c-3d1b-4d53-8270-231c32754954" xlink:type="arc" order="24"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityExTransitionPeriod_e6b88ff5-8cce-48d5-bd77-14ce85a30c80" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityExTransitionPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_364f94a0-daee-468d-a0cd-68ecc1b034bd" xlink:to="loc_dei_EntityExTransitionPeriod_e6b88ff5-8cce-48d5-bd77-14ce85a30c80" xlink:type="arc" order="25"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_IcfrAuditorAttestationFlag_30b75b19-dcd5-4093-8f47-f2e1251f56ef" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_IcfrAuditorAttestationFlag"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_364f94a0-daee-468d-a0cd-68ecc1b034bd" xlink:to="loc_dei_IcfrAuditorAttestationFlag_30b75b19-dcd5-4093-8f47-f2e1251f56ef" xlink:type="arc" order="26"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityShellCompany_3167b03b-2c43-41a6-9fc2-019a82310cfd" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityShellCompany"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_364f94a0-daee-468d-a0cd-68ecc1b034bd" xlink:to="loc_dei_EntityShellCompany_3167b03b-2c43-41a6-9fc2-019a82310cfd" xlink:type="arc" order="27"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityPublicFloat_0fc99775-32e9-4969-8a33-44f738190ea7" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityPublicFloat"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_364f94a0-daee-468d-a0cd-68ecc1b034bd" xlink:to="loc_dei_EntityPublicFloat_0fc99775-32e9-4969-8a33-44f738190ea7" xlink:type="arc" order="28"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCommonStockSharesOutstanding_d5ef1969-2492-42f1-a253-c1659cf34107" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityCommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_364f94a0-daee-468d-a0cd-68ecc1b034bd" xlink:to="loc_dei_EntityCommonStockSharesOutstanding_d5ef1969-2492-42f1-a253-c1659cf34107" xlink:type="arc" order="29"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentsIncorporatedByReferenceTextBlock_02a6ea64-94eb-463e-bae1-fce79859c26e" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_DocumentsIncorporatedByReferenceTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_364f94a0-daee-468d-a0cd-68ecc1b034bd" xlink:to="loc_dei_DocumentsIncorporatedByReferenceTextBlock_02a6ea64-94eb-463e-bae1-fce79859c26e" xlink:type="arc" order="30"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCentralIndexKey_f6f6a7e4-7ed7-41b3-8f57-56601b0308f9" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityCentralIndexKey"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_364f94a0-daee-468d-a0cd-68ecc1b034bd" xlink:to="loc_dei_EntityCentralIndexKey_f6f6a7e4-7ed7-41b3-8f57-56601b0308f9" xlink:type="arc" order="31"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentFiscalYearFocus_0528c60b-8a37-433c-9e26-6296e7cbc10b" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_DocumentFiscalYearFocus"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_364f94a0-daee-468d-a0cd-68ecc1b034bd" xlink:to="loc_dei_DocumentFiscalYearFocus_0528c60b-8a37-433c-9e26-6296e7cbc10b" xlink:type="arc" order="32"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentFiscalPeriodFocus_bb61476d-91c4-4c34-b1b6-95d3f98d0833" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_DocumentFiscalPeriodFocus"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_364f94a0-daee-468d-a0cd-68ecc1b034bd" xlink:to="loc_dei_DocumentFiscalPeriodFocus_bb61476d-91c4-4c34-b1b6-95d3f98d0833" xlink:type="arc" order="33"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_AmendmentFlag_cbb39c27-0cc6-4fb3-9688-10fae06d0666" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_AmendmentFlag"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_364f94a0-daee-468d-a0cd-68ecc1b034bd" xlink:to="loc_dei_AmendmentFlag_cbb39c27-0cc6-4fb3-9688-10fae06d0666" xlink:type="arc" order="34"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentInformationTable_4206c86f-0ace-4987-a4c4-d56c64d1a660" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_DocumentInformationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_dei_DocumentInformationLineItems_364f94a0-daee-468d-a0cd-68ecc1b034bd" xlink:to="loc_dei_DocumentInformationTable_4206c86f-0ace-4987-a4c4-d56c64d1a660" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_3d4d3f1a-e7ed-4745-9282-e7973f66e357" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_dei_DocumentInformationTable_4206c86f-0ace-4987-a4c4-d56c64d1a660" xlink:to="loc_us-gaap_StatementClassOfStockAxis_3d4d3f1a-e7ed-4745-9282-e7973f66e357" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_3d4d3f1a-e7ed-4745-9282-e7973f66e357_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_3d4d3f1a-e7ed-4745-9282-e7973f66e357" xlink:to="loc_us-gaap_ClassOfStockDomain_3d4d3f1a-e7ed-4745-9282-e7973f66e357_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_a8a6debf-d7a2-4e61-bc83-06fd6260b1cf" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_3d4d3f1a-e7ed-4745-9282-e7973f66e357" xlink:to="loc_us-gaap_ClassOfStockDomain_a8a6debf-d7a2-4e61-bc83-06fd6260b1cf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_b1e8aaf1-198a-4bb1-be37-21af86d51d81" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_a8a6debf-d7a2-4e61-bc83-06fd6260b1cf" xlink:to="loc_us-gaap_CommonClassAMember_b1e8aaf1-198a-4bb1-be37-21af86d51d81" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassBMember_014621fa-09a3-4b20-9d37-edf92f14bfcb" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonClassBMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_a8a6debf-d7a2-4e61-bc83-06fd6260b1cf" xlink:to="loc_us-gaap_CommonClassBMember_014621fa-09a3-4b20-9d37-edf92f14bfcb" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pwp.com/role/ConsolidatedStatementsofFinancialCondition" xlink:type="simple" xlink:href="pwp-20221231.xsd#ConsolidatedStatementsofFinancialCondition"/>
  <link:definitionLink xlink:role="http://pwp.com/role/ConsolidatedStatementsofFinancialCondition" xlink:type="extended" id="i95b637b4b62f4b72adca16b9e232b5fb_ConsolidatedStatementsofFinancialCondition">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_b37ba5b1-5605-4360-9e60-d5b3e9beb88e" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsAbstract_d94e6956-7afd-439b-8bf6-f1590a6e7dc4" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_b37ba5b1-5605-4360-9e60-d5b3e9beb88e" xlink:to="loc_us-gaap_AssetsAbstract_d94e6956-7afd-439b-8bf6-f1590a6e7dc4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_96b5fa13-7771-4f9a-9369-1100df1c4990" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_d94e6956-7afd-439b-8bf6-f1590a6e7dc4" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_96b5fa13-7771-4f9a-9369-1100df1c4990" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCash_ae1b34d0-bb6b-444e-a0f6-21648447f967" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RestrictedCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_d94e6956-7afd-439b-8bf6-f1590a6e7dc4" xlink:to="loc_us-gaap_RestrictedCash_ae1b34d0-bb6b-444e-a0f6-21648447f967" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermInvestments_3bc58081-ec5f-4199-af27-af37a6b63bdc" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShortTermInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_d94e6956-7afd-439b-8bf6-f1590a6e7dc4" xlink:to="loc_us-gaap_ShortTermInvestments_3bc58081-ec5f-4199-af27-af37a6b63bdc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableNet_5320cbe6-4720-4920-97f0-229612c13858" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AccountsReceivableNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_d94e6956-7afd-439b-8bf6-f1590a6e7dc4" xlink:to="loc_us-gaap_AccountsReceivableNet_5320cbe6-4720-4920-97f0-229612c13858" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DueFromRelatedParties_cadef33a-958d-456a-8c19-57a1b712c5b3" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DueFromRelatedParties"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_d94e6956-7afd-439b-8bf6-f1590a6e7dc4" xlink:to="loc_us-gaap_DueFromRelatedParties_cadef33a-958d-456a-8c19-57a1b712c5b3" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_83893230-d244-43af-932f-399fa9b53763" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_d94e6956-7afd-439b-8bf6-f1590a6e7dc4" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_83893230-d244-43af-932f-399fa9b53763" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_4ae892fb-e438-4f3f-af15-d6c9e9d1eb85" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FiniteLivedIntangibleAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_d94e6956-7afd-439b-8bf6-f1590a6e7dc4" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNet_4ae892fb-e438-4f3f-af15-d6c9e9d1eb85" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_5ea43b86-a781-48ef-ba55-75c1cbc1d7e2" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_d94e6956-7afd-439b-8bf6-f1590a6e7dc4" xlink:to="loc_us-gaap_Goodwill_5ea43b86-a781-48ef-ba55-75c1cbc1d7e2" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrepaidExpenseAndOtherAssets_4439755c-c90a-4efa-bff4-f45330305089" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PrepaidExpenseAndOtherAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_d94e6956-7afd-439b-8bf6-f1590a6e7dc4" xlink:to="loc_us-gaap_PrepaidExpenseAndOtherAssets_4439755c-c90a-4efa-bff4-f45330305089" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAsset_9ac1c079-b544-490a-9db2-469539ff0c36" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OperatingLeaseRightOfUseAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_d94e6956-7afd-439b-8bf6-f1590a6e7dc4" xlink:to="loc_us-gaap_OperatingLeaseRightOfUseAsset_9ac1c079-b544-490a-9db2-469539ff0c36" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxAssetsNet_92b0e016-bd5e-409e-b1b7-1b41c6a78596" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DeferredIncomeTaxAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_d94e6956-7afd-439b-8bf6-f1590a6e7dc4" xlink:to="loc_us-gaap_DeferredIncomeTaxAssetsNet_92b0e016-bd5e-409e-b1b7-1b41c6a78596" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_5524a4dc-42f3-4eef-ac53-c62a3e61a759" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_d94e6956-7afd-439b-8bf6-f1590a6e7dc4" xlink:to="loc_us-gaap_Assets_5524a4dc-42f3-4eef-ac53-c62a3e61a759" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_63d17488-1949-42c4-9019-7cebfb829f61" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LiabilitiesAndStockholdersEquityAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_b37ba5b1-5605-4360-9e60-d5b3e9beb88e" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_63d17488-1949-42c4-9019-7cebfb829f61" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeRelatedLiabilitiesCurrentAndNoncurrent_961e2443-ac17-4171-b9a6-80e854c908a0" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EmployeeRelatedLiabilitiesCurrentAndNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_63d17488-1949-42c4-9019-7cebfb829f61" xlink:to="loc_us-gaap_EmployeeRelatedLiabilitiesCurrentAndNoncurrent_961e2443-ac17-4171-b9a6-80e854c908a0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCompensationLiabilityCurrentAndNoncurrent_6113f06e-073a-4729-8a9b-bd57dbdc68b6" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DeferredCompensationLiabilityCurrentAndNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_63d17488-1949-42c4-9019-7cebfb829f61" xlink:to="loc_us-gaap_DeferredCompensationLiabilityCurrentAndNoncurrent_6113f06e-073a-4729-8a9b-bd57dbdc68b6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent_7cd766ef-8d1e-41f0-ab12-837116702587" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_63d17488-1949-42c4-9019-7cebfb829f61" xlink:to="loc_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent_7cd766ef-8d1e-41f0-ab12-837116702587" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiability_f92f0f0e-89a1-4ea3-aef3-c52a8fe6a476" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ContractWithCustomerLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_63d17488-1949-42c4-9019-7cebfb829f61" xlink:to="loc_us-gaap_ContractWithCustomerLiability_f92f0f0e-89a1-4ea3-aef3-c52a8fe6a476" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiability_55ed18bc-0304-4ddd-9731-177fb99ce6bd" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OperatingLeaseLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_63d17488-1949-42c4-9019-7cebfb829f61" xlink:to="loc_us-gaap_OperatingLeaseLiability_55ed18bc-0304-4ddd-9731-177fb99ce6bd" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilities_fa198bab-f343-48f6-91c7-8934b0036cf2" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_63d17488-1949-42c4-9019-7cebfb829f61" xlink:to="loc_us-gaap_DerivativeLiabilities_fa198bab-f343-48f6-91c7-8934b0036cf2" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_AmountDuePursuantToTaxReceivableAgreement_f2b070c2-2c5e-429b-b3dd-09e1f803d750" xlink:href="pwp-20221231.xsd#pwp_AmountDuePursuantToTaxReceivableAgreement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_63d17488-1949-42c4-9019-7cebfb829f61" xlink:to="loc_pwp_AmountDuePursuantToTaxReceivableAgreement_f2b070c2-2c5e-429b-b3dd-09e1f803d750" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Liabilities_6ccfc46a-7b1c-4959-bdbd-2cf996552f98" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_Liabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_63d17488-1949-42c4-9019-7cebfb829f61" xlink:to="loc_us-gaap_Liabilities_6ccfc46a-7b1c-4959-bdbd-2cf996552f98" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommitmentsAndContingencies_91226ad2-10de-4ce9-bed3-6f0c67edeb94" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommitmentsAndContingencies"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_63d17488-1949-42c4-9019-7cebfb829f61" xlink:to="loc_us-gaap_CommitmentsAndContingencies_91226ad2-10de-4ce9-bed3-6f0c67edeb94" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockValue_7f62c03e-398a-485a-b5a3-f8dec0054df6" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonStockValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_63d17488-1949-42c4-9019-7cebfb829f61" xlink:to="loc_us-gaap_CommonStockValue_7f62c03e-398a-485a-b5a3-f8dec0054df6" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockValue_7d54f263-c707-4b16-a48a-30fb4d2a29db" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PreferredStockValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_63d17488-1949-42c4-9019-7cebfb829f61" xlink:to="loc_us-gaap_PreferredStockValue_7d54f263-c707-4b16-a48a-30fb4d2a29db" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalCommonStock_ae48c3a0-617e-4c83-9743-ae8f180a11ce" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AdditionalPaidInCapitalCommonStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_63d17488-1949-42c4-9019-7cebfb829f61" xlink:to="loc_us-gaap_AdditionalPaidInCapitalCommonStock_ae48c3a0-617e-4c83-9743-ae8f180a11ce" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_c76f41d5-8833-4365-a8e3-4b1b1df6576a" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RetainedEarningsAccumulatedDeficit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_63d17488-1949-42c4-9019-7cebfb829f61" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_c76f41d5-8833-4365-a8e3-4b1b1df6576a" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_80232183-0929-4443-a148-ea356c8e675b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_63d17488-1949-42c4-9019-7cebfb829f61" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_80232183-0929-4443-a148-ea356c8e675b" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockValue_90351093-312e-4dd5-b3f0-60f64317d3a8" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TreasuryStockValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_63d17488-1949-42c4-9019-7cebfb829f61" xlink:to="loc_us-gaap_TreasuryStockValue_90351093-312e-4dd5-b3f0-60f64317d3a8" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_0c88543e-deae-4926-b1a8-9c4463a733e1" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_63d17488-1949-42c4-9019-7cebfb829f61" xlink:to="loc_us-gaap_StockholdersEquity_0c88543e-deae-4926-b1a8-9c4463a733e1" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterest_02062db1-bbbf-4315-9751-7f06bc56d4c1" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_MinorityInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_63d17488-1949-42c4-9019-7cebfb829f61" xlink:to="loc_us-gaap_MinorityInterest_02062db1-bbbf-4315-9751-7f06bc56d4c1" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_26e8422a-b3e6-4777-aa41-f8cab3054555" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_63d17488-1949-42c4-9019-7cebfb829f61" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_26e8422a-b3e6-4777-aa41-f8cab3054555" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity_7b2c506d-3c26-422e-9cdb-74830547c5d6" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LiabilitiesAndStockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_63d17488-1949-42c4-9019-7cebfb829f61" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquity_7b2c506d-3c26-422e-9cdb-74830547c5d6" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_258a94b2-74b2-4e4f-8e68-4d815024e0e2" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_b37ba5b1-5605-4360-9e60-d5b3e9beb88e" xlink:to="loc_us-gaap_StatementTable_258a94b2-74b2-4e4f-8e68-4d815024e0e2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_5a8dae65-682a-4f88-8238-07f0cb8a8e0b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_258a94b2-74b2-4e4f-8e68-4d815024e0e2" xlink:to="loc_us-gaap_StatementClassOfStockAxis_5a8dae65-682a-4f88-8238-07f0cb8a8e0b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_5a8dae65-682a-4f88-8238-07f0cb8a8e0b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_5a8dae65-682a-4f88-8238-07f0cb8a8e0b" xlink:to="loc_us-gaap_ClassOfStockDomain_5a8dae65-682a-4f88-8238-07f0cb8a8e0b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_1fb273d8-db3d-43f9-a74e-8e62c34e8560" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_5a8dae65-682a-4f88-8238-07f0cb8a8e0b" xlink:to="loc_us-gaap_ClassOfStockDomain_1fb273d8-db3d-43f9-a74e-8e62c34e8560" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_60085469-70a4-4554-ab9f-cd5193b1f149" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_1fb273d8-db3d-43f9-a74e-8e62c34e8560" xlink:to="loc_us-gaap_CommonClassAMember_60085469-70a4-4554-ab9f-cd5193b1f149" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassBMember_3e43e204-9d24-4092-ade5-a0531f3d1d20" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonClassBMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_1fb273d8-db3d-43f9-a74e-8e62c34e8560" xlink:to="loc_us-gaap_CommonClassBMember_3e43e204-9d24-4092-ade5-a0531f3d1d20" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pwp.com/role/ConsolidatedStatementsofFinancialConditionParenthetical" xlink:type="simple" xlink:href="pwp-20221231.xsd#ConsolidatedStatementsofFinancialConditionParenthetical"/>
  <link:definitionLink xlink:role="http://pwp.com/role/ConsolidatedStatementsofFinancialConditionParenthetical" xlink:type="extended" id="i7c87572454f6442083c107379e1b6736_ConsolidatedStatementsofFinancialConditionParenthetical">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_98c02b08-d866-47ea-8726-5c379827112a" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockParOrStatedValuePerShare_a5571843-db79-433f-9a0b-78bb2585a846" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonStockParOrStatedValuePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_98c02b08-d866-47ea-8726-5c379827112a" xlink:to="loc_us-gaap_CommonStockParOrStatedValuePerShare_a5571843-db79-433f-9a0b-78bb2585a846" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesAuthorized_09685a1b-929d-4cde-8f46-0d2f0d35d090" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonStockSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_98c02b08-d866-47ea-8726-5c379827112a" xlink:to="loc_us-gaap_CommonStockSharesAuthorized_09685a1b-929d-4cde-8f46-0d2f0d35d090" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesIssued_7a895b7e-d630-4b16-96fe-455082fc7c44" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonStockSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_98c02b08-d866-47ea-8726-5c379827112a" xlink:to="loc_us-gaap_CommonStockSharesIssued_7a895b7e-d630-4b16-96fe-455082fc7c44" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_e104ef93-1746-4633-bab6-9332def33489" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_98c02b08-d866-47ea-8726-5c379827112a" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_e104ef93-1746-4633-bab6-9332def33489" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesIssued_5831034f-102a-4396-be72-fc9b4e9f734f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PreferredStockSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_98c02b08-d866-47ea-8726-5c379827112a" xlink:to="loc_us-gaap_PreferredStockSharesIssued_5831034f-102a-4396-be72-fc9b4e9f734f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesOutstanding_739ed48e-2d94-43fa-9887-b01d45300d6a" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PreferredStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_98c02b08-d866-47ea-8726-5c379827112a" xlink:to="loc_us-gaap_PreferredStockSharesOutstanding_739ed48e-2d94-43fa-9887-b01d45300d6a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockParOrStatedValuePerShare_316ce9dc-18af-4485-b067-98b41b91dbe6" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PreferredStockParOrStatedValuePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_98c02b08-d866-47ea-8726-5c379827112a" xlink:to="loc_us-gaap_PreferredStockParOrStatedValuePerShare_316ce9dc-18af-4485-b067-98b41b91dbe6" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesAuthorized_c02ae0c0-5112-4d11-8697-3524efafac99" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PreferredStockSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_98c02b08-d866-47ea-8726-5c379827112a" xlink:to="loc_us-gaap_PreferredStockSharesAuthorized_c02ae0c0-5112-4d11-8697-3524efafac99" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonShares_b19293dd-df55-4ebe-be5d-61163f416649" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TreasuryStockCommonShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_98c02b08-d866-47ea-8726-5c379827112a" xlink:to="loc_us-gaap_TreasuryStockCommonShares_b19293dd-df55-4ebe-be5d-61163f416649" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_ad91af9d-445c-4994-8a39-708bbeabcd00" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_98c02b08-d866-47ea-8726-5c379827112a" xlink:to="loc_us-gaap_StatementTable_ad91af9d-445c-4994-8a39-708bbeabcd00" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_4f3b48d3-924e-4d9d-9a27-deb70a7cfaeb" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_ad91af9d-445c-4994-8a39-708bbeabcd00" xlink:to="loc_us-gaap_StatementClassOfStockAxis_4f3b48d3-924e-4d9d-9a27-deb70a7cfaeb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_4f3b48d3-924e-4d9d-9a27-deb70a7cfaeb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_4f3b48d3-924e-4d9d-9a27-deb70a7cfaeb" xlink:to="loc_us-gaap_ClassOfStockDomain_4f3b48d3-924e-4d9d-9a27-deb70a7cfaeb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_6c136586-2a32-4c67-aa58-48125ebd1354" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_4f3b48d3-924e-4d9d-9a27-deb70a7cfaeb" xlink:to="loc_us-gaap_ClassOfStockDomain_6c136586-2a32-4c67-aa58-48125ebd1354" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_6ef1bff5-0d5e-4a88-a9c9-dcd0ada8d43b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_6c136586-2a32-4c67-aa58-48125ebd1354" xlink:to="loc_us-gaap_CommonClassAMember_6ef1bff5-0d5e-4a88-a9c9-dcd0ada8d43b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassBMember_a453ae3e-3ba5-46ad-b130-9712d6684ca7" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonClassBMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_6c136586-2a32-4c67-aa58-48125ebd1354" xlink:to="loc_us-gaap_CommonClassBMember_a453ae3e-3ba5-46ad-b130-9712d6684ca7" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pwp.com/role/ConsolidatedStatementsofChangesinEquity" xlink:type="simple" xlink:href="pwp-20221231.xsd#ConsolidatedStatementsofChangesinEquity"/>
  <link:definitionLink xlink:role="http://pwp.com/role/ConsolidatedStatementsofChangesinEquity" xlink:type="extended" id="i44c9e1be3c85431193fb64caef145e32_ConsolidatedStatementsofChangesinEquity">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_9db54b71-6ac0-44e3-9d07-c8f77ed60c73" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_3fab60ee-d108-4149-bb0f-d4247fcd96fc" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_9db54b71-6ac0-44e3-9d07-c8f77ed60c73" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_3fab60ee-d108-4149-bb0f-d4247fcd96fc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnersCapital_0c24b9ec-ed2a-4bba-a12d-98659e58452b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PartnersCapital"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_3fab60ee-d108-4149-bb0f-d4247fcd96fc" xlink:to="loc_us-gaap_PartnersCapital_0c24b9ec-ed2a-4bba-a12d-98659e58452b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_ae1ab373-e86d-4308-a709-b9449aa84dd4" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_3fab60ee-d108-4149-bb0f-d4247fcd96fc" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_ae1ab373-e86d-4308-a709-b9449aa84dd4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonShares_c3980eb7-f176-490f-be23-cac9181a2661" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TreasuryStockCommonShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_3fab60ee-d108-4149-bb0f-d4247fcd96fc" xlink:to="loc_us-gaap_TreasuryStockCommonShares_c3980eb7-f176-490f-be23-cac9181a2661" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_7fb961b1-04a0-4daa-927b-697fc495845f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_3fab60ee-d108-4149-bb0f-d4247fcd96fc" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_7fb961b1-04a0-4daa-927b-697fc495845f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_CumulativeEffectOfAccountingChange_9ff3fd05-ab6f-42e3-b6f7-48e35858a5a9" xlink:href="pwp-20221231.xsd#pwp_CumulativeEffectOfAccountingChange"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_3fab60ee-d108-4149-bb0f-d4247fcd96fc" xlink:to="loc_pwp_CumulativeEffectOfAccountingChange_9ff3fd05-ab6f-42e3-b6f7-48e35858a5a9" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_a8f56771-96ff-4976-9abb-2d8b51e514f2" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ProfitLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_3fab60ee-d108-4149-bb0f-d4247fcd96fc" xlink:to="loc_us-gaap_ProfitLoss_a8f56771-96ff-4976-9abb-2d8b51e514f2" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnersCapitalAccountUnitBasedCompensation_a010f08b-dfee-4094-83ef-71d96ce9ff2d" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PartnersCapitalAccountUnitBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_3fab60ee-d108-4149-bb0f-d4247fcd96fc" xlink:to="loc_us-gaap_PartnersCapitalAccountUnitBasedCompensation_a010f08b-dfee-4094-83ef-71d96ce9ff2d" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnersCapitalAccountDistributions_80f150e7-8381-4957-8c05-572d401a1076" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PartnersCapitalAccountDistributions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_3fab60ee-d108-4149-bb0f-d4247fcd96fc" xlink:to="loc_us-gaap_PartnersCapitalAccountDistributions_80f150e7-8381-4957-8c05-572d401a1076" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnersCapitalOther_00e2f485-0d62-4120-9bb8-ad688f98f279" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PartnersCapitalOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_3fab60ee-d108-4149-bb0f-d4247fcd96fc" xlink:to="loc_us-gaap_PartnersCapitalOther_00e2f485-0d62-4120-9bb8-ad688f98f279" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax_a22a980a-5744-4b51-a1f1-77eca29a963b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_3fab60ee-d108-4149-bb0f-d4247fcd96fc" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax_a22a980a-5744-4b51-a1f1-77eca29a963b" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_EffectOfBusinessCombination_57a5cdb6-0693-435e-bf3f-51ce86e3d00d" xlink:href="pwp-20221231.xsd#pwp_EffectOfBusinessCombination"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_3fab60ee-d108-4149-bb0f-d4247fcd96fc" xlink:to="loc_pwp_EffectOfBusinessCombination_57a5cdb6-0693-435e-bf3f-51ce86e3d00d" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_EffectOfBusinessCombinationOnShare_34a06c45-568b-4b30-a016-7dee893230db" xlink:href="pwp-20221231.xsd#pwp_EffectOfBusinessCombinationOnShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_3fab60ee-d108-4149-bb0f-d4247fcd96fc" xlink:to="loc_pwp_EffectOfBusinessCombinationOnShare_34a06c45-568b-4b30-a016-7dee893230db" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_PartnersCapitalAccountDistributionsAfterBusinessCombination_a3bfa609-682a-4136-81c2-b4c9c04cf7b7" xlink:href="pwp-20221231.xsd#pwp_PartnersCapitalAccountDistributionsAfterBusinessCombination"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_3fab60ee-d108-4149-bb0f-d4247fcd96fc" xlink:to="loc_pwp_PartnersCapitalAccountDistributionsAfterBusinessCombination_a3bfa609-682a-4136-81c2-b4c9c04cf7b7" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationOtherLongtermIncentivePlansRequisiteServicePeriodRecognition_dd6174d8-ad35-4bf1-9af5-41259bea3aa7" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationOtherLongtermIncentivePlansRequisiteServicePeriodRecognition"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_3fab60ee-d108-4149-bb0f-d4247fcd96fc" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationOtherLongtermIncentivePlansRequisiteServicePeriodRecognition_dd6174d8-ad35-4bf1-9af5-41259bea3aa7" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockSharesIssuedNetOfSharesForTaxWithholdings_ade63560-b5be-49eb-9dcc-2ce84445f204" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RestrictedStockSharesIssuedNetOfSharesForTaxWithholdings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_3fab60ee-d108-4149-bb0f-d4247fcd96fc" xlink:to="loc_us-gaap_RestrictedStockSharesIssuedNetOfSharesForTaxWithholdings_ade63560-b5be-49eb-9dcc-2ce84445f204" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation_5fba69d4-27a4-4c8c-8c33-61080ce6d602" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_3fab60ee-d108-4149-bb0f-d4247fcd96fc" xlink:to="loc_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation_5fba69d4-27a4-4c8c-8c33-61080ce6d602" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Dividends_3017dd4d-4790-4d2b-ba64-3a66ae41f282" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_Dividends"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_3fab60ee-d108-4149-bb0f-d4247fcd96fc" xlink:to="loc_us-gaap_Dividends_3017dd4d-4790-4d2b-ba64-3a66ae41f282" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityOther_7d252d10-92b1-47da-b2f9-0fcff7e94534" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockholdersEquityOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_3fab60ee-d108-4149-bb0f-d4247fcd96fc" xlink:to="loc_us-gaap_StockholdersEquityOther_7d252d10-92b1-47da-b2f9-0fcff7e94534" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockSharesAcquired_dc993ba8-bdd0-42b6-8577-fdf0c0e0fe78" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TreasuryStockSharesAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_3fab60ee-d108-4149-bb0f-d4247fcd96fc" xlink:to="loc_us-gaap_TreasuryStockSharesAcquired_dc993ba8-bdd0-42b6-8577-fdf0c0e0fe78" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_9e846e6e-c91a-4289-8f07-1d03638986e2" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TreasuryStockValueAcquiredCostMethod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_3fab60ee-d108-4149-bb0f-d4247fcd96fc" xlink:to="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_9e846e6e-c91a-4289-8f07-1d03638986e2" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_AdjustmentsToAdditionalPaidInCapitalChangeInOwnershipInterestValue_a8f13f63-dca5-428b-a00e-86dc8b54bcdb" xlink:href="pwp-20221231.xsd#pwp_AdjustmentsToAdditionalPaidInCapitalChangeInOwnershipInterestValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_3fab60ee-d108-4149-bb0f-d4247fcd96fc" xlink:to="loc_pwp_AdjustmentsToAdditionalPaidInCapitalChangeInOwnershipInterestValue_a8f13f63-dca5-428b-a00e-86dc8b54bcdb" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_67dc18c7-3880-451a-a312-1a13e49e6b6b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_3fab60ee-d108-4149-bb0f-d4247fcd96fc" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_67dc18c7-3880-451a-a312-1a13e49e6b6b" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockValueSharesIssuedNetOfTaxWithholdings_674d6fda-50e3-4194-b79e-a857679ee582" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RestrictedStockValueSharesIssuedNetOfTaxWithholdings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_3fab60ee-d108-4149-bb0f-d4247fcd96fc" xlink:to="loc_us-gaap_RestrictedStockValueSharesIssuedNetOfTaxWithholdings_674d6fda-50e3-4194-b79e-a857679ee582" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_f4eed597-e582-4f4f-a3a3-64b6123ff0cd" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_3fab60ee-d108-4149-bb0f-d4247fcd96fc" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_f4eed597-e582-4f4f-a3a3-64b6123ff0cd" xlink:type="arc" order="24"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_0967b6f4-ae8c-41a9-b4bb-c3f2487c6d0a" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockIssuedDuringPeriodValueNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_3fab60ee-d108-4149-bb0f-d4247fcd96fc" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_0967b6f4-ae8c-41a9-b4bb-c3f2487c6d0a" xlink:type="arc" order="25"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_973009ef-a97c-41d8-91cf-d75a137e1b5c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_3fab60ee-d108-4149-bb0f-d4247fcd96fc" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_973009ef-a97c-41d8-91cf-d75a137e1b5c" xlink:type="arc" order="26"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities_92d8308f-f04d-4898-a116-2ec5be9275ce" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_3fab60ee-d108-4149-bb0f-d4247fcd96fc" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities_92d8308f-f04d-4898-a116-2ec5be9275ce" xlink:type="arc" order="27"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_StockIssuedDuringPeriodSharesWarrantsExercised_4e57b80f-b8f2-4318-91c7-27efda86dc3a" xlink:href="pwp-20221231.xsd#pwp_StockIssuedDuringPeriodSharesWarrantsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_3fab60ee-d108-4149-bb0f-d4247fcd96fc" xlink:to="loc_pwp_StockIssuedDuringPeriodSharesWarrantsExercised_4e57b80f-b8f2-4318-91c7-27efda86dc3a" xlink:type="arc" order="28"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_StockIssuedDuringPeriodValueWarrantsExercised_2a8be223-d791-4823-922d-5564d511f5b2" xlink:href="pwp-20221231.xsd#pwp_StockIssuedDuringPeriodValueWarrantsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_3fab60ee-d108-4149-bb0f-d4247fcd96fc" xlink:to="loc_pwp_StockIssuedDuringPeriodValueWarrantsExercised_2a8be223-d791-4823-922d-5564d511f5b2" xlink:type="arc" order="29"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnersCapital_b5d497e6-b1d1-41c4-b449-d8dfaf84978a" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PartnersCapital"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_d5d7db3d-8ed0-476c-b475-97d885dd8046" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonShares_5f6fd386-25e8-45be-852e-74a22f92800c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TreasuryStockCommonShares"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_9e8aa2f6-8b56-40d1-9ac6-4b873de02d97" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_e7e86fa5-5d34-45db-82cd-9c14b614198c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_9db54b71-6ac0-44e3-9d07-c8f77ed60c73" xlink:to="loc_us-gaap_StatementTable_e7e86fa5-5d34-45db-82cd-9c14b614198c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnerTypeOfPartnersCapitalAccountAxis_e2ce1fd2-ecdd-43a2-9d6d-3ed3ef6be127" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PartnerTypeOfPartnersCapitalAccountAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_e7e86fa5-5d34-45db-82cd-9c14b614198c" xlink:to="loc_us-gaap_PartnerTypeOfPartnersCapitalAccountAxis_e2ce1fd2-ecdd-43a2-9d6d-3ed3ef6be127" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnerTypeOfPartnersCapitalAccountNameDomain_e2ce1fd2-ecdd-43a2-9d6d-3ed3ef6be127_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PartnerTypeOfPartnersCapitalAccountNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PartnerTypeOfPartnersCapitalAccountAxis_e2ce1fd2-ecdd-43a2-9d6d-3ed3ef6be127" xlink:to="loc_us-gaap_PartnerTypeOfPartnersCapitalAccountNameDomain_e2ce1fd2-ecdd-43a2-9d6d-3ed3ef6be127_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnerTypeOfPartnersCapitalAccountNameDomain_c3f756b6-9873-4916-8cce-a7c7dbdceb63" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PartnerTypeOfPartnersCapitalAccountNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PartnerTypeOfPartnersCapitalAccountAxis_e2ce1fd2-ecdd-43a2-9d6d-3ed3ef6be127" xlink:to="loc_us-gaap_PartnerTypeOfPartnersCapitalAccountNameDomain_c3f756b6-9873-4916-8cce-a7c7dbdceb63" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedPartnerMember_7d893423-14ac-451e-83f5-ba54435f4698" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LimitedPartnerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PartnerTypeOfPartnersCapitalAccountNameDomain_c3f756b6-9873-4916-8cce-a7c7dbdceb63" xlink:to="loc_us-gaap_LimitedPartnerMember_7d893423-14ac-451e-83f5-ba54435f4698" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_7ac686e9-9087-4973-8507-d91257a76c3e" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_e7e86fa5-5d34-45db-82cd-9c14b614198c" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_7ac686e9-9087-4973-8507-d91257a76c3e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_7ac686e9-9087-4973-8507-d91257a76c3e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_7ac686e9-9087-4973-8507-d91257a76c3e" xlink:to="loc_us-gaap_EquityComponentDomain_7ac686e9-9087-4973-8507-d91257a76c3e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_989f1246-b8d2-4186-bfce-f5eadd01b2d9" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_7ac686e9-9087-4973-8507-d91257a76c3e" xlink:to="loc_us-gaap_EquityComponentDomain_989f1246-b8d2-4186-bfce-f5eadd01b2d9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_898d8221-6455-42bf-8412-291ef1b2587c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_989f1246-b8d2-4186-bfce-f5eadd01b2d9" xlink:to="loc_us-gaap_CommonStockMember_898d8221-6455-42bf-8412-291ef1b2587c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonMember_81c13f84-a329-4bbe-83b3-9597d24cbf6d" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TreasuryStockCommonMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_989f1246-b8d2-4186-bfce-f5eadd01b2d9" xlink:to="loc_us-gaap_TreasuryStockCommonMember_81c13f84-a329-4bbe-83b3-9597d24cbf6d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_c914b430-7366-4f3a-9568-58ad56267835" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_989f1246-b8d2-4186-bfce-f5eadd01b2d9" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_c914b430-7366-4f3a-9568-58ad56267835" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_de9e51af-17e6-48b5-aa66-512fb17216b8" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_989f1246-b8d2-4186-bfce-f5eadd01b2d9" xlink:to="loc_us-gaap_RetainedEarningsMember_de9e51af-17e6-48b5-aa66-512fb17216b8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_9230a245-7d76-4451-ad2b-c2e7ebe5bf30" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_989f1246-b8d2-4186-bfce-f5eadd01b2d9" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_9230a245-7d76-4451-ad2b-c2e7ebe5bf30" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncontrollingInterestMember_c8ca09f6-0138-411c-98f0-9de8a8996bd9" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NoncontrollingInterestMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_989f1246-b8d2-4186-bfce-f5eadd01b2d9" xlink:to="loc_us-gaap_NoncontrollingInterestMember_c8ca09f6-0138-411c-98f0-9de8a8996bd9" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_e4312843-cbfa-49c1-a930-e05b8189636c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_e7e86fa5-5d34-45db-82cd-9c14b614198c" xlink:to="loc_us-gaap_StatementClassOfStockAxis_e4312843-cbfa-49c1-a930-e05b8189636c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_e4312843-cbfa-49c1-a930-e05b8189636c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_e4312843-cbfa-49c1-a930-e05b8189636c" xlink:to="loc_us-gaap_ClassOfStockDomain_e4312843-cbfa-49c1-a930-e05b8189636c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_dfdad9fb-879c-4d52-bf42-5d7deec020b2" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_e4312843-cbfa-49c1-a930-e05b8189636c" xlink:to="loc_us-gaap_ClassOfStockDomain_dfdad9fb-879c-4d52-bf42-5d7deec020b2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_906d9909-ea20-4d93-a21c-d97a03d3ad37" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_dfdad9fb-879c-4d52-bf42-5d7deec020b2" xlink:to="loc_us-gaap_CommonClassAMember_906d9909-ea20-4d93-a21c-d97a03d3ad37" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassBMember_a1e688b2-b120-42d7-a80e-d6df5663ecd1" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonClassBMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_dfdad9fb-879c-4d52-bf42-5d7deec020b2" xlink:to="loc_us-gaap_CommonClassBMember_a1e688b2-b120-42d7-a80e-d6df5663ecd1" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pwp.com/role/ConsolidatedStatementsofChangesinEquityParenthetical" xlink:type="simple" xlink:href="pwp-20221231.xsd#ConsolidatedStatementsofChangesinEquityParenthetical"/>
  <link:definitionLink xlink:role="http://pwp.com/role/ConsolidatedStatementsofChangesinEquityParenthetical" xlink:type="extended" id="i9c775fe8251844b0985ac175117d0318_ConsolidatedStatementsofChangesinEquityParenthetical">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_7123b733-b1a4-4ac0-b5de-47dc19d7983b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockDividendsPerShareDeclared_b107e789-defe-46c5-91ef-dfc49e7caaf3" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonStockDividendsPerShareDeclared"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_7123b733-b1a4-4ac0-b5de-47dc19d7983b" xlink:to="loc_us-gaap_CommonStockDividendsPerShareDeclared_b107e789-defe-46c5-91ef-dfc49e7caaf3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_8c3c6658-850a-42b4-949b-60da44d516ea" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_7123b733-b1a4-4ac0-b5de-47dc19d7983b" xlink:to="loc_us-gaap_StatementTable_8c3c6658-850a-42b4-949b-60da44d516ea" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_b0cc885a-baa9-4854-92aa-826618990b8a" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_8c3c6658-850a-42b4-949b-60da44d516ea" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_b0cc885a-baa9-4854-92aa-826618990b8a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_b0cc885a-baa9-4854-92aa-826618990b8a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_b0cc885a-baa9-4854-92aa-826618990b8a" xlink:to="loc_us-gaap_EquityComponentDomain_b0cc885a-baa9-4854-92aa-826618990b8a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_60b71f1b-b7ca-454e-9c10-12a9644f23c6" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_b0cc885a-baa9-4854-92aa-826618990b8a" xlink:to="loc_us-gaap_EquityComponentDomain_60b71f1b-b7ca-454e-9c10-12a9644f23c6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_7b89d598-637e-4ba5-a71c-5cc91d115973" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_60b71f1b-b7ca-454e-9c10-12a9644f23c6" xlink:to="loc_us-gaap_CommonStockMember_7b89d598-637e-4ba5-a71c-5cc91d115973" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_09219ea1-c80b-4835-b64a-22b79932491d" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_8c3c6658-850a-42b4-949b-60da44d516ea" xlink:to="loc_us-gaap_StatementClassOfStockAxis_09219ea1-c80b-4835-b64a-22b79932491d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_09219ea1-c80b-4835-b64a-22b79932491d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_09219ea1-c80b-4835-b64a-22b79932491d" xlink:to="loc_us-gaap_ClassOfStockDomain_09219ea1-c80b-4835-b64a-22b79932491d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_63ee0535-2219-4f83-88df-81f7db2c19f6" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_09219ea1-c80b-4835-b64a-22b79932491d" xlink:to="loc_us-gaap_ClassOfStockDomain_63ee0535-2219-4f83-88df-81f7db2c19f6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_917fd9ba-7e76-41b9-aaf8-31411d457ee6" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_63ee0535-2219-4f83-88df-81f7db2c19f6" xlink:to="loc_us-gaap_CommonClassAMember_917fd9ba-7e76-41b9-aaf8-31411d457ee6" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pwp.com/role/EquityBasedCompensationTables" xlink:type="simple" xlink:href="pwp-20221231.xsd#EquityBasedCompensationTables"/>
  <link:definitionLink xlink:role="http://pwp.com/role/EquityBasedCompensationTables" xlink:type="extended" id="ib2feea3414204f21b7fd593f4bbcce3f_EquityBasedCompensationTables">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_085e81e0-ce05-4a4a-a6d7-a624744f6a55" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationPerformanceSharesAwardUnvestedActivityTableTextBlock_b8f4c322-6f27-438e-987b-49c67c4fed22" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationPerformanceSharesAwardUnvestedActivityTableTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_085e81e0-ce05-4a4a-a6d7-a624744f6a55" xlink:to="loc_us-gaap_ShareBasedCompensationPerformanceSharesAwardUnvestedActivityTableTextBlock_b8f4c322-6f27-438e-987b-49c67c4fed22" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_ScheduleOfShareBasedPaymentAwardOtherThanStockOptionsValuationAssumptionsTableTextBlock_ae28de6d-f6e8-4ce5-b4e6-f1a2a07b5286" xlink:href="pwp-20221231.xsd#pwp_ScheduleOfShareBasedPaymentAwardOtherThanStockOptionsValuationAssumptionsTableTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_085e81e0-ce05-4a4a-a6d7-a624744f6a55" xlink:to="loc_pwp_ScheduleOfShareBasedPaymentAwardOtherThanStockOptionsValuationAssumptionsTableTextBlock_ae28de6d-f6e8-4ce5-b4e6-f1a2a07b5286" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationRestrictedStockUnitsAwardActivityTableTextBlock_465dc315-1b18-46d3-ba51-152d0168d652" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfShareBasedCompensationRestrictedStockUnitsAwardActivityTableTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_085e81e0-ce05-4a4a-a6d7-a624744f6a55" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationRestrictedStockUnitsAwardActivityTableTextBlock_465dc315-1b18-46d3-ba51-152d0168d652" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfCompensationCostForShareBasedPaymentArrangementsAllocationOfShareBasedCompensationCostsByPlanTableTextBlock_63116c38-4851-4e67-9e67-2c262823e0f6" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfCompensationCostForShareBasedPaymentArrangementsAllocationOfShareBasedCompensationCostsByPlanTableTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_085e81e0-ce05-4a4a-a6d7-a624744f6a55" xlink:to="loc_us-gaap_ScheduleOfCompensationCostForShareBasedPaymentArrangementsAllocationOfShareBasedCompensationCostsByPlanTableTextBlock_63116c38-4851-4e67-9e67-2c262823e0f6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_f47318a8-ea3e-4e38-abc9-3d3451f74a64" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_085e81e0-ce05-4a4a-a6d7-a624744f6a55" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_f47318a8-ea3e-4e38-abc9-3d3451f74a64" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_44f9d197-1976-4c7f-be71-d3ae9972677c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_f47318a8-ea3e-4e38-abc9-3d3451f74a64" xlink:to="loc_us-gaap_AwardTypeAxis_44f9d197-1976-4c7f-be71-d3ae9972677c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_44f9d197-1976-4c7f-be71-d3ae9972677c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_44f9d197-1976-4c7f-be71-d3ae9972677c" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_44f9d197-1976-4c7f-be71-d3ae9972677c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_856c3404-b8d4-4ae8-9569-a4c8a95d331a" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_44f9d197-1976-4c7f-be71-d3ae9972677c" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_856c3404-b8d4-4ae8-9569-a4c8a95d331a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_TransactionPoolPsusMember_c276b3f2-6f32-4977-b315-412de85bc6ba" xlink:href="pwp-20221231.xsd#pwp_TransactionPoolPsusMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_856c3404-b8d4-4ae8-9569-a4c8a95d331a" xlink:to="loc_pwp_TransactionPoolPsusMember_c276b3f2-6f32-4977-b315-412de85bc6ba" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_TransactionPoolRsusMember_8355b15f-e3c7-4954-9dd0-ad2d6dad9b76" xlink:href="pwp-20221231.xsd#pwp_TransactionPoolRsusMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_856c3404-b8d4-4ae8-9569-a4c8a95d331a" xlink:to="loc_pwp_TransactionPoolRsusMember_8355b15f-e3c7-4954-9dd0-ad2d6dad9b76" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_LongTermIncentiveAwardsMember_dbf342ef-b3e1-4c09-b5e1-76b72de516a6" xlink:href="pwp-20221231.xsd#pwp_LongTermIncentiveAwardsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_856c3404-b8d4-4ae8-9569-a4c8a95d331a" xlink:to="loc_pwp_LongTermIncentiveAwardsMember_dbf342ef-b3e1-4c09-b5e1-76b72de516a6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_GeneralRsusMember_f7514d1f-7aa1-4561-be6f-9d85a38023ff" xlink:href="pwp-20221231.xsd#pwp_GeneralRsusMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_856c3404-b8d4-4ae8-9569-a4c8a95d331a" xlink:to="loc_pwp_GeneralRsusMember_f7514d1f-7aa1-4561-be6f-9d85a38023ff" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pwp.com/role/SummaryofSignificantAccountingPoliciesAdditionalInformationDetails" xlink:type="simple" xlink:href="pwp-20221231.xsd#SummaryofSignificantAccountingPoliciesAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://pwp.com/role/SummaryofSignificantAccountingPoliciesAdditionalInformationDetails" xlink:type="extended" id="i293e902b9a2045fbb77ca1c26be5bfd1_SummaryofSignificantAccountingPoliciesAdditionalInformationDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProductInformationLineItems_e80ea2ec-b0dc-4779-b122-c267e0b1ba4a" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ProductInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableNet_2fb6caf3-6f2d-468e-bb4a-3047c61a4266" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AccountsReceivableNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductInformationLineItems_e80ea2ec-b0dc-4779-b122-c267e0b1ba4a" xlink:to="loc_us-gaap_AccountsReceivableNet_2fb6caf3-6f2d-468e-bb4a-3047c61a4266" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsReceivable_6b4604b2-8ca9-49b8-bdf5-8f0d5d8af987" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncreaseDecreaseInAccountsReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductInformationLineItems_e80ea2ec-b0dc-4779-b122-c267e0b1ba4a" xlink:to="loc_us-gaap_IncreaseDecreaseInAccountsReceivable_6b4604b2-8ca9-49b8-bdf5-8f0d5d8af987" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfProductInformationTable_2c000093-8e45-40e5-badf-9dc028da8966" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfProductInformationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ProductInformationLineItems_e80ea2ec-b0dc-4779-b122-c267e0b1ba4a" xlink:to="loc_us-gaap_ScheduleOfProductInformationTable_2c000093-8e45-40e5-badf-9dc028da8966" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_62bc30f6-d423-4b9e-80a5-40e6e1f08c5f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ConcentrationRiskByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfProductInformationTable_2c000093-8e45-40e5-badf-9dc028da8966" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_62bc30f6-d423-4b9e-80a5-40e6e1f08c5f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_62bc30f6-d423-4b9e-80a5-40e6e1f08c5f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_62bc30f6-d423-4b9e-80a5-40e6e1f08c5f" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_62bc30f6-d423-4b9e-80a5-40e6e1f08c5f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_d6aa61b4-4003-4cf5-9c20-f0a2131a44b7" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_62bc30f6-d423-4b9e-80a5-40e6e1f08c5f" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_d6aa61b4-4003-4cf5-9c20-f0a2131a44b7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerConcentrationRiskMember_6db2f3bb-4ab7-422d-811b-4db5a107633c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CustomerConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_d6aa61b4-4003-4cf5-9c20-f0a2131a44b7" xlink:to="loc_us-gaap_CustomerConcentrationRiskMember_6db2f3bb-4ab7-422d-811b-4db5a107633c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_9dbc4c97-1261-4123-9679-88459d5ef9b9" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfProductInformationTable_2c000093-8e45-40e5-badf-9dc028da8966" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_9dbc4c97-1261-4123-9679-88459d5ef9b9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_9dbc4c97-1261-4123-9679-88459d5ef9b9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_9dbc4c97-1261-4123-9679-88459d5ef9b9" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_9dbc4c97-1261-4123-9679-88459d5ef9b9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_f174fa11-fba9-478d-9ef6-cc9d23d98eb9" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_9dbc4c97-1261-4123-9679-88459d5ef9b9" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_f174fa11-fba9-478d-9ef6-cc9d23d98eb9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableMember_ca09f2bf-ba16-4e64-9d20-7d11481fd072" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AccountsReceivableMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_f174fa11-fba9-478d-9ef6-cc9d23d98eb9" xlink:to="loc_us-gaap_AccountsReceivableMember_ca09f2bf-ba16-4e64-9d20-7d11481fd072" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_b53ec27f-2070-4136-ae16-7e86f4c99b3e" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_MajorCustomersAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfProductInformationTable_2c000093-8e45-40e5-badf-9dc028da8966" xlink:to="loc_srt_MajorCustomersAxis_b53ec27f-2070-4136-ae16-7e86f4c99b3e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_b53ec27f-2070-4136-ae16-7e86f4c99b3e_default" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_b53ec27f-2070-4136-ae16-7e86f4c99b3e" xlink:to="loc_srt_NameOfMajorCustomerDomain_b53ec27f-2070-4136-ae16-7e86f4c99b3e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_34f11fbb-6908-4aa4-807f-c9a15aac455e" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_b53ec27f-2070-4136-ae16-7e86f4c99b3e" xlink:to="loc_srt_NameOfMajorCustomerDomain_34f11fbb-6908-4aa4-807f-c9a15aac455e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_TwoCustomersMember_5487f3b0-bbee-466a-8085-abe62d575532" xlink:href="pwp-20221231.xsd#pwp_TwoCustomersMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_34f11fbb-6908-4aa4-807f-c9a15aac455e" xlink:to="loc_pwp_TwoCustomersMember_5487f3b0-bbee-466a-8085-abe62d575532" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_92f27057-4dad-4cdb-bbfc-0018ad296aec" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfProductInformationTable_2c000093-8e45-40e5-badf-9dc028da8966" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_92f27057-4dad-4cdb-bbfc-0018ad296aec" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_92f27057-4dad-4cdb-bbfc-0018ad296aec_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_92f27057-4dad-4cdb-bbfc-0018ad296aec" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_92f27057-4dad-4cdb-bbfc-0018ad296aec_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_b12fccd1-0fce-443b-9bce-3c6c57beef86" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_92f27057-4dad-4cdb-bbfc-0018ad296aec" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_b12fccd1-0fce-443b-9bce-3c6c57beef86" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_f9daf7c8-8233-42c9-81a3-623a4011f23d" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_b12fccd1-0fce-443b-9bce-3c6c57beef86" xlink:to="loc_us-gaap_SubsequentEventMember_f9daf7c8-8233-42c9-81a3-623a4011f23d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableInterestEntityLineItems_5fb825c3-5eeb-4b7f-a1fa-b949cae298a3" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_VariableInterestEntityLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_b7169693-dcd0-4db2-ac94-bfc7bd1d61ea" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_5fb825c3-5eeb-4b7f-a1fa-b949cae298a3" xlink:to="loc_us-gaap_Assets_b7169693-dcd0-4db2-ac94-bfc7bd1d61ea" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCurrencyTransactionGainLossBeforeTax_e75d71ff-33de-4b22-bf27-19296f2296c1" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ForeignCurrencyTransactionGainLossBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_5fb825c3-5eeb-4b7f-a1fa-b949cae298a3" xlink:to="loc_us-gaap_ForeignCurrencyTransactionGainLossBeforeTax_e75d71ff-33de-4b22-bf27-19296f2296c1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReconciliationOfAssetsFromSegmentToConsolidatedTable_adab8160-73e2-473a-afff-1c1192442451" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ReconciliationOfAssetsFromSegmentToConsolidatedTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_5fb825c3-5eeb-4b7f-a1fa-b949cae298a3" xlink:to="loc_us-gaap_ReconciliationOfAssetsFromSegmentToConsolidatedTable_adab8160-73e2-473a-afff-1c1192442451" xlink:type="arc" order="2" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesAxis_944de14d-c6e3-4027-88ae-c6193c50d964" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ConsolidatedEntitiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ReconciliationOfAssetsFromSegmentToConsolidatedTable_adab8160-73e2-473a-afff-1c1192442451" xlink:to="loc_srt_ConsolidatedEntitiesAxis_944de14d-c6e3-4027-88ae-c6193c50d964" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_944de14d-c6e3-4027-88ae-c6193c50d964_default" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidatedEntitiesAxis_944de14d-c6e3-4027-88ae-c6193c50d964" xlink:to="loc_srt_ConsolidatedEntitiesDomain_944de14d-c6e3-4027-88ae-c6193c50d964_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_d6ca2c51-d397-4fe3-a6f1-d53cb1aab6eb" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidatedEntitiesAxis_944de14d-c6e3-4027-88ae-c6193c50d964" xlink:to="loc_srt_ConsolidatedEntitiesDomain_d6ca2c51-d397-4fe3-a6f1-d53cb1aab6eb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_PWPOpCoMember_6df5ae9b-1a91-403c-bd51-8e0ac9d74c92" xlink:href="pwp-20221231.xsd#pwp_PWPOpCoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidatedEntitiesDomain_d6ca2c51-d397-4fe3-a6f1-d53cb1aab6eb" xlink:to="loc_pwp_PWPOpCoMember_6df5ae9b-1a91-403c-bd51-8e0ac9d74c92" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_1a4dd38f-2114-4488-b478-f9693e20eda5" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_fe78d9db-42ba-4eea-86e3-83d499b1b1b1" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_1a4dd38f-2114-4488-b478-f9693e20eda5" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_fe78d9db-42ba-4eea-86e3-83d499b1b1b1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_86e9215b-2b81-4c16-bda2-1658698e425e" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_1a4dd38f-2114-4488-b478-f9693e20eda5" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_86e9215b-2b81-4c16-bda2-1658698e425e" xlink:type="arc" order="3" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_e182ec1e-d470-4192-b3f4-156c5b9912dd" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_86e9215b-2b81-4c16-bda2-1658698e425e" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_e182ec1e-d470-4192-b3f4-156c5b9912dd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_e182ec1e-d470-4192-b3f4-156c5b9912dd_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_e182ec1e-d470-4192-b3f4-156c5b9912dd" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_e182ec1e-d470-4192-b3f4-156c5b9912dd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_f81860b3-1194-4b46-9443-3040748227a6" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_e182ec1e-d470-4192-b3f4-156c5b9912dd" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_f81860b3-1194-4b46-9443-3040748227a6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_FurnitureFixturesAndEquipmentMember_31c94a56-74bf-47e7-aa24-dfe038fea7b4" xlink:href="pwp-20221231.xsd#pwp_FurnitureFixturesAndEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_f81860b3-1194-4b46-9443-3040748227a6" xlink:to="loc_pwp_FurnitureFixturesAndEquipmentMember_31c94a56-74bf-47e7-aa24-dfe038fea7b4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_SoftwareMember_f0ad04ad-d57f-4f9b-9102-2aaf7c4767d2" xlink:href="pwp-20221231.xsd#pwp_SoftwareMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_f81860b3-1194-4b46-9443-3040748227a6" xlink:to="loc_pwp_SoftwareMember_f0ad04ad-d57f-4f9b-9102-2aaf7c4767d2" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pwp.com/role/BusinessCombinationAdditionalInformationDetails" xlink:type="simple" xlink:href="pwp-20221231.xsd#BusinessCombinationAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://pwp.com/role/BusinessCombinationAdditionalInformationDetails" xlink:type="extended" id="i61dec8a4ab614dfaac1f8f689948e61e_BusinessCombinationAdditionalInformationDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_278e91dc-83a2-4cca-b987-74b2c796ffe3" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationDescriptionAbstract_fbe00172-b17d-4931-bc4b-a4d8bc4a5f42" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BusinessCombinationDescriptionAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_278e91dc-83a2-4cca-b987-74b2c796ffe3" xlink:to="loc_us-gaap_BusinessCombinationDescriptionAbstract_fbe00172-b17d-4931-bc4b-a4d8bc4a5f42" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesSubscribedButUnissued_25a10890-467d-40b1-bc04-5d4d8d4fdfdc" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonStockSharesSubscribedButUnissued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationDescriptionAbstract_fbe00172-b17d-4931-bc4b-a4d8bc4a5f42" xlink:to="loc_us-gaap_CommonStockSharesSubscribedButUnissued_25a10890-467d-40b1-bc04-5d4d8d4fdfdc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesSubscriptions_7892c35e-b583-405d-8f42-de42d56cc0ae" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonStockSharesSubscriptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationDescriptionAbstract_fbe00172-b17d-4931-bc4b-a4d8bc4a5f42" xlink:to="loc_us-gaap_CommonStockSharesSubscriptions_7892c35e-b583-405d-8f42-de42d56cc0ae" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_CommonStockForfeited_9bdb2264-a1ae-4195-966b-a39d7b7d46f6" xlink:href="pwp-20221231.xsd#pwp_CommonStockForfeited"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationDescriptionAbstract_fbe00172-b17d-4931-bc4b-a4d8bc4a5f42" xlink:to="loc_pwp_CommonStockForfeited_9bdb2264-a1ae-4195-966b-a39d7b7d46f6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_CommonStockForfeitedValuePerShare_54f0b922-355a-4f22-a268-120121fe47bc" xlink:href="pwp-20221231.xsd#pwp_CommonStockForfeitedValuePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationDescriptionAbstract_fbe00172-b17d-4931-bc4b-a4d8bc4a5f42" xlink:to="loc_pwp_CommonStockForfeitedValuePerShare_54f0b922-355a-4f22-a268-120121fe47bc" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesGross_389f495f-93c0-4c53-b27c-38202e286115" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PaymentsToAcquireBusinessesGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationDescriptionAbstract_fbe00172-b17d-4931-bc4b-a4d8bc4a5f42" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesGross_389f495f-93c0-4c53-b27c-38202e286115" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_009634f0-2af1-41d8-90be-4288c07b5c7e" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationDescriptionAbstract_fbe00172-b17d-4931-bc4b-a4d8bc4a5f42" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_009634f0-2af1-41d8-90be-4288c07b5c7e" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_CommonStockNumberOfVotingRights_fe9db616-930d-45c2-aa2b-c4aa7aa21d15" xlink:href="pwp-20221231.xsd#pwp_CommonStockNumberOfVotingRights"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationDescriptionAbstract_fbe00172-b17d-4931-bc4b-a4d8bc4a5f42" xlink:to="loc_pwp_CommonStockNumberOfVotingRights_fe9db616-930d-45c2-aa2b-c4aa7aa21d15" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfConvertibleDebt_f29b811b-5d14-4fdc-8177-0cf8bfd8aa1d" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RepaymentsOfConvertibleDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationDescriptionAbstract_fbe00172-b17d-4931-bc4b-a4d8bc4a5f42" xlink:to="loc_us-gaap_RepaymentsOfConvertibleDebt_f29b811b-5d14-4fdc-8177-0cf8bfd8aa1d" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfLinesOfCredit_fba51c82-79b2-497e-8d05-f06cc6214c01" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RepaymentsOfLinesOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationDescriptionAbstract_fbe00172-b17d-4931-bc4b-a4d8bc4a5f42" xlink:to="loc_us-gaap_RepaymentsOfLinesOfCredit_fba51c82-79b2-497e-8d05-f06cc6214c01" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_1d7e9297-af2a-4cb0-96d4-c7267bbb2191" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationDescriptionAbstract_fbe00172-b17d-4931-bc4b-a4d8bc4a5f42" xlink:to="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_1d7e9297-af2a-4cb0-96d4-c7267bbb2191" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnersCapitalAccountRedemptions_0d39389c-cd26-42a2-b893-8a2485ddc8d7" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PartnersCapitalAccountRedemptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationDescriptionAbstract_fbe00172-b17d-4931-bc4b-a4d8bc4a5f42" xlink:to="loc_us-gaap_PartnersCapitalAccountRedemptions_0d39389c-cd26-42a2-b893-8a2485ddc8d7" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilities_22860bd8-453a-44d3-9ae0-f6635dc2693b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationDescriptionAbstract_fbe00172-b17d-4931-bc4b-a4d8bc4a5f42" xlink:to="loc_us-gaap_DerivativeLiabilities_22860bd8-453a-44d3-9ae0-f6635dc2693b" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationAcquisitionRelatedCosts_a3394623-dd93-41b4-972a-e95eaa67c364" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BusinessCombinationAcquisitionRelatedCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationDescriptionAbstract_fbe00172-b17d-4931-bc4b-a4d8bc4a5f42" xlink:to="loc_us-gaap_BusinessCombinationAcquisitionRelatedCosts_a3394623-dd93-41b4-972a-e95eaa67c364" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionCostOfAcquiredEntityTransactionCosts_b704183c-6b08-4360-bb68-6cf0333a62a0" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BusinessAcquisitionCostOfAcquiredEntityTransactionCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationDescriptionAbstract_fbe00172-b17d-4931-bc4b-a4d8bc4a5f42" xlink:to="loc_us-gaap_BusinessAcquisitionCostOfAcquiredEntityTransactionCosts_b704183c-6b08-4360-bb68-6cf0333a62a0" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_64147717-9334-40a7-b475-7e6d59125533" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationDescriptionAbstract_fbe00172-b17d-4931-bc4b-a4d8bc4a5f42" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_64147717-9334-40a7-b475-7e6d59125533" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_821c7bb5-31f2-4280-8fa1-0ee078f5519d" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_278e91dc-83a2-4cca-b987-74b2c796ffe3" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_821c7bb5-31f2-4280-8fa1-0ee078f5519d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_59d466e6-1386-413f-a143-7e807c766618" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_821c7bb5-31f2-4280-8fa1-0ee078f5519d" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_59d466e6-1386-413f-a143-7e807c766618" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_59d466e6-1386-413f-a143-7e807c766618_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_59d466e6-1386-413f-a143-7e807c766618" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_59d466e6-1386-413f-a143-7e807c766618_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_74d7b199-60c8-4967-88f8-564688b8b461" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_59d466e6-1386-413f-a143-7e807c766618" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_74d7b199-60c8-4967-88f8-564688b8b461" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_PipeInvestorsMember_03aadea8-9893-4003-bd28-9c81036c8ce0" xlink:href="pwp-20221231.xsd#pwp_PipeInvestorsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_74d7b199-60c8-4967-88f8-564688b8b461" xlink:to="loc_pwp_PipeInvestorsMember_03aadea8-9893-4003-bd28-9c81036c8ce0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_SponsorRelatedPipeInvestorsMember_d2665697-a92d-40d0-8f4a-a0c38fda0226" xlink:href="pwp-20221231.xsd#pwp_SponsorRelatedPipeInvestorsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_74d7b199-60c8-4967-88f8-564688b8b461" xlink:to="loc_pwp_SponsorRelatedPipeInvestorsMember_d2665697-a92d-40d0-8f4a-a0c38fda0226" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_SponsorMember_72bb797e-095f-4934-bbcf-c6bbb8697d52" xlink:href="pwp-20221231.xsd#pwp_SponsorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_74d7b199-60c8-4967-88f8-564688b8b461" xlink:to="loc_pwp_SponsorMember_72bb797e-095f-4934-bbcf-c6bbb8697d52" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_FtivAndOtherPartiesMember_d0acdaee-1498-40af-a0a6-66a225a9cab3" xlink:href="pwp-20221231.xsd#pwp_FtivAndOtherPartiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_74d7b199-60c8-4967-88f8-564688b8b461" xlink:to="loc_pwp_FtivAndOtherPartiesMember_d0acdaee-1498-40af-a0a6-66a225a9cab3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_ElectingIlpsMember_b1fb6b3b-cdc8-42fe-9995-790d6a42de10" xlink:href="pwp-20221231.xsd#pwp_ElectingIlpsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_74d7b199-60c8-4967-88f8-564688b8b461" xlink:to="loc_pwp_ElectingIlpsMember_b1fb6b3b-cdc8-42fe-9995-790d6a42de10" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_ElectingFormerWorkingPartnersMember_901205a1-b0eb-4698-96c7-30ee24433601" xlink:href="pwp-20221231.xsd#pwp_ElectingFormerWorkingPartnersMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_74d7b199-60c8-4967-88f8-564688b8b461" xlink:to="loc_pwp_ElectingFormerWorkingPartnersMember_901205a1-b0eb-4698-96c7-30ee24433601" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_4e5897ee-a2e6-47d1-8cb7-c56770641a01" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_821c7bb5-31f2-4280-8fa1-0ee078f5519d" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_4e5897ee-a2e6-47d1-8cb7-c56770641a01" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_4e5897ee-a2e6-47d1-8cb7-c56770641a01_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_4e5897ee-a2e6-47d1-8cb7-c56770641a01" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_4e5897ee-a2e6-47d1-8cb7-c56770641a01_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_b0b6aaeb-4b95-41c1-bf21-3a6ba4d21a01" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_4e5897ee-a2e6-47d1-8cb7-c56770641a01" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_b0b6aaeb-4b95-41c1-bf21-3a6ba4d21a01" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConvertibleDebtMember_75f1dcfd-e046-4e85-a963-5ca8aa6438cf" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ConvertibleDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_b0b6aaeb-4b95-41c1-bf21-3a6ba4d21a01" xlink:to="loc_us-gaap_ConvertibleDebtMember_75f1dcfd-e046-4e85-a963-5ca8aa6438cf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_e72f022e-fc32-49cb-aa6e-f7d18a6a6728" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_821c7bb5-31f2-4280-8fa1-0ee078f5519d" xlink:to="loc_us-gaap_CreditFacilityAxis_e72f022e-fc32-49cb-aa6e-f7d18a6a6728" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_e72f022e-fc32-49cb-aa6e-f7d18a6a6728_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_e72f022e-fc32-49cb-aa6e-f7d18a6a6728" xlink:to="loc_us-gaap_CreditFacilityDomain_e72f022e-fc32-49cb-aa6e-f7d18a6a6728_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_94bf15cc-7619-4693-b3e7-fdaa9e855f0a" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_e72f022e-fc32-49cb-aa6e-f7d18a6a6728" xlink:to="loc_us-gaap_CreditFacilityDomain_94bf15cc-7619-4693-b3e7-fdaa9e855f0a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_f0a59e64-6e24-490b-90c0-b5710d208f8b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_94bf15cc-7619-4693-b3e7-fdaa9e855f0a" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_f0a59e64-6e24-490b-90c0-b5710d208f8b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_d7ddf52e-7f61-4365-bfec-d97fd27a5128" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_821c7bb5-31f2-4280-8fa1-0ee078f5519d" xlink:to="loc_us-gaap_StatementClassOfStockAxis_d7ddf52e-7f61-4365-bfec-d97fd27a5128" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_d7ddf52e-7f61-4365-bfec-d97fd27a5128_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_d7ddf52e-7f61-4365-bfec-d97fd27a5128" xlink:to="loc_us-gaap_ClassOfStockDomain_d7ddf52e-7f61-4365-bfec-d97fd27a5128_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_0b87c288-9331-4206-b5a9-c12dbc2b5fb8" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_d7ddf52e-7f61-4365-bfec-d97fd27a5128" xlink:to="loc_us-gaap_ClassOfStockDomain_0b87c288-9331-4206-b5a9-c12dbc2b5fb8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_52064892-de34-4a8e-bc86-3067202bb358" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_0b87c288-9331-4206-b5a9-c12dbc2b5fb8" xlink:to="loc_us-gaap_CommonClassAMember_52064892-de34-4a8e-bc86-3067202bb358" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassBMember_c7cbac8d-0251-43e6-8b1e-f4ca6c524878" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonClassBMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_0b87c288-9331-4206-b5a9-c12dbc2b5fb8" xlink:to="loc_us-gaap_CommonClassBMember_c7cbac8d-0251-43e6-8b1e-f4ca6c524878" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_CommonClassB1Member_a3eb24dc-1767-4925-b2a4-1bbbc4661d57" xlink:href="pwp-20221231.xsd#pwp_CommonClassB1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_0b87c288-9331-4206-b5a9-c12dbc2b5fb8" xlink:to="loc_pwp_CommonClassB1Member_a3eb24dc-1767-4925-b2a4-1bbbc4661d57" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_ClassB2CommonStockMember_3cddc104-f336-4c03-98f8-77ea5840b6e8" xlink:href="pwp-20221231.xsd#pwp_ClassB2CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_0b87c288-9331-4206-b5a9-c12dbc2b5fb8" xlink:to="loc_pwp_ClassB2CommonStockMember_3cddc104-f336-4c03-98f8-77ea5840b6e8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_eccce391-5d8d-4d91-a71a-1d833464a755" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_821c7bb5-31f2-4280-8fa1-0ee078f5519d" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_eccce391-5d8d-4d91-a71a-1d833464a755" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_eccce391-5d8d-4d91-a71a-1d833464a755_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_eccce391-5d8d-4d91-a71a-1d833464a755" xlink:to="loc_us-gaap_EquityComponentDomain_eccce391-5d8d-4d91-a71a-1d833464a755_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_17cae937-85e3-4231-8590-c239cc7c7fa7" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_eccce391-5d8d-4d91-a71a-1d833464a755" xlink:to="loc_us-gaap_EquityComponentDomain_17cae937-85e3-4231-8590-c239cc7c7fa7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_PublicWarrantMember_de9ed620-0d7d-4f50-ba49-fbfba2fc6690" xlink:href="pwp-20221231.xsd#pwp_PublicWarrantMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_17cae937-85e3-4231-8590-c239cc7c7fa7" xlink:to="loc_pwp_PublicWarrantMember_de9ed620-0d7d-4f50-ba49-fbfba2fc6690" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_PrivateWarrantMember_c4d9b18d-007e-4a6d-826f-0c4a36a23770" xlink:href="pwp-20221231.xsd#pwp_PrivateWarrantMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_17cae937-85e3-4231-8590-c239cc7c7fa7" xlink:to="loc_pwp_PrivateWarrantMember_c4d9b18d-007e-4a6d-826f-0c4a36a23770" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pwp.com/role/RevenueandReceivablesfromContractswithCustomersScheduleofDisaggregationofRevenueDetails" xlink:type="simple" xlink:href="pwp-20221231.xsd#RevenueandReceivablesfromContractswithCustomersScheduleofDisaggregationofRevenueDetails"/>
  <link:definitionLink xlink:role="http://pwp.com/role/RevenueandReceivablesfromContractswithCustomersScheduleofDisaggregationofRevenueDetails" xlink:type="extended" id="id3624c70b0b245d58a1dca63796d5fc4_RevenueandReceivablesfromContractswithCustomersScheduleofDisaggregationofRevenueDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_ef99b7e7-d9d4-4504-9766-52c503ef5940" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_54c40b7a-efe3-4f66-a3b6-e42b26b721c6" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_ef99b7e7-d9d4-4504-9766-52c503ef5940" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_54c40b7a-efe3-4f66-a3b6-e42b26b721c6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_090db001-5b2f-4898-a735-986c4164c8c7" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_ef99b7e7-d9d4-4504-9766-52c503ef5940" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_090db001-5b2f-4898-a735-986c4164c8c7" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TimingOfTransferOfGoodOrServiceAxis_a96b3884-e2fa-4424-9af1-1d74b0033ca4" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TimingOfTransferOfGoodOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_090db001-5b2f-4898-a735-986c4164c8c7" xlink:to="loc_us-gaap_TimingOfTransferOfGoodOrServiceAxis_a96b3884-e2fa-4424-9af1-1d74b0033ca4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_a96b3884-e2fa-4424-9af1-1d74b0033ca4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TimingOfTransferOfGoodOrServiceDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TimingOfTransferOfGoodOrServiceAxis_a96b3884-e2fa-4424-9af1-1d74b0033ca4" xlink:to="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_a96b3884-e2fa-4424-9af1-1d74b0033ca4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_71c4fa88-4c49-493e-9f66-379f30928d8e" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TimingOfTransferOfGoodOrServiceDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TimingOfTransferOfGoodOrServiceAxis_a96b3884-e2fa-4424-9af1-1d74b0033ca4" xlink:to="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_71c4fa88-4c49-493e-9f66-379f30928d8e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransferredOverTimeMember_c006cec5-bdc2-4080-8a1b-7a5c7b79ac2b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TransferredOverTimeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_71c4fa88-4c49-493e-9f66-379f30928d8e" xlink:to="loc_us-gaap_TransferredOverTimeMember_c006cec5-bdc2-4080-8a1b-7a5c7b79ac2b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransferredAtPointInTimeMember_8e3c3b77-4a1c-41ce-9356-b354c58de0bb" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TransferredAtPointInTimeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_71c4fa88-4c49-493e-9f66-379f30928d8e" xlink:to="loc_us-gaap_TransferredAtPointInTimeMember_8e3c3b77-4a1c-41ce-9356-b354c58de0bb" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pwp.com/role/RevenueandReceivablesfromContractswithCustomersAdditionalInformationDetails1" xlink:type="simple" xlink:href="pwp-20221231.xsd#RevenueandReceivablesfromContractswithCustomersAdditionalInformationDetails1"/>
  <link:definitionLink xlink:role="http://pwp.com/role/RevenueandReceivablesfromContractswithCustomersAdditionalInformationDetails1" xlink:type="extended" id="i6aa58533ad264b1b8204075ce4193f12_RevenueandReceivablesfromContractswithCustomersAdditionalInformationDetails1">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_53b3caa2-b4a6-4c80-af85-38669c9e5788" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligation_ae52bdd1-d81a-486a-a660-735f5ffff531" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RevenueRemainingPerformanceObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_53b3caa2-b4a6-4c80-af85-38669c9e5788" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligation_ae52bdd1-d81a-486a-a660-735f5ffff531" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_4a231ad2-24bc-4359-ae12-8e46231b0287" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_53b3caa2-b4a6-4c80-af85-38669c9e5788" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_4a231ad2-24bc-4359-ae12-8e46231b0287" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_eacd300b-7f69-4cab-b5e7-6c01c84480b7" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_53b3caa2-b4a6-4c80-af85-38669c9e5788" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_eacd300b-7f69-4cab-b5e7-6c01c84480b7" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_fce60ba1-a752-4687-942d-b1773acbb722" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_eacd300b-7f69-4cab-b5e7-6c01c84480b7" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_fce60ba1-a752-4687-942d-b1773acbb722" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pwp.com/role/RevenueandReceivablesfromContractswithCustomersAdditionalInformationDetails1_1" xlink:type="simple" xlink:href="pwp-20221231.xsd#RevenueandReceivablesfromContractswithCustomersAdditionalInformationDetails1_1"/>
  <link:definitionLink xlink:role="http://pwp.com/role/RevenueandReceivablesfromContractswithCustomersAdditionalInformationDetails1_1" xlink:type="extended" id="ic53a635006db4665bc1ee583007bced6_RevenueandReceivablesfromContractswithCustomersAdditionalInformationDetails1_1">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_53b3caa2-b4a6-4c80-af85-38669c9e5788" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligation_ae52bdd1-d81a-486a-a660-735f5ffff531" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RevenueRemainingPerformanceObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_53b3caa2-b4a6-4c80-af85-38669c9e5788" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligation_ae52bdd1-d81a-486a-a660-735f5ffff531" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_4a231ad2-24bc-4359-ae12-8e46231b0287" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_53b3caa2-b4a6-4c80-af85-38669c9e5788" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_4a231ad2-24bc-4359-ae12-8e46231b0287" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_eacd300b-7f69-4cab-b5e7-6c01c84480b7" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_53b3caa2-b4a6-4c80-af85-38669c9e5788" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_eacd300b-7f69-4cab-b5e7-6c01c84480b7" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pwp.com/role/RevenueandReceivablesfromContractswithCustomersScheduleofAllowanceforCreditLossesDetails" xlink:type="simple" xlink:href="pwp-20221231.xsd#RevenueandReceivablesfromContractswithCustomersScheduleofAllowanceforCreditLossesDetails"/>
  <link:definitionLink xlink:role="http://pwp.com/role/RevenueandReceivablesfromContractswithCustomersScheduleofAllowanceforCreditLossesDetails" xlink:type="extended" id="ifa02bdf65042445596b010a5dff0b8eb_RevenueandReceivablesfromContractswithCustomersScheduleofAllowanceforCreditLossesDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_886e46e4-5123-4ddd-a503-94d94912f8b1" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableRollforward_b5d90b17-54fe-4067-af17-94ae4b2d5052" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivableRollforward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_886e46e4-5123-4ddd-a503-94d94912f8b1" xlink:to="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableRollforward_b5d90b17-54fe-4067-af17-94ae4b2d5052" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllowanceForDoubtfulAccountsReceivable_f4116e7b-3f58-45e4-b47a-36c93c45e25e" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableRollforward_b5d90b17-54fe-4067-af17-94ae4b2d5052" xlink:to="loc_us-gaap_AllowanceForDoubtfulAccountsReceivable_f4116e7b-3f58-45e4-b47a-36c93c45e25e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProvisionForDoubtfulAccounts_de020951-62ed-44e2-bdd9-091866696bf6" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ProvisionForDoubtfulAccounts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableRollforward_b5d90b17-54fe-4067-af17-94ae4b2d5052" xlink:to="loc_us-gaap_ProvisionForDoubtfulAccounts_de020951-62ed-44e2-bdd9-091866696bf6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableWriteOffs_79505efe-cb9a-4ca2-872e-87bbabc65659" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivableWriteOffs"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableRollforward_b5d90b17-54fe-4067-af17-94ae4b2d5052" xlink:to="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableWriteOffs_79505efe-cb9a-4ca2-872e-87bbabc65659" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableRecoveries_dbca22cd-09d8-48c5-b431-337ada25251a" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivableRecoveries"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableRollforward_b5d90b17-54fe-4067-af17-94ae4b2d5052" xlink:to="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableRecoveries_dbca22cd-09d8-48c5-b431-337ada25251a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_AllowanceForDoubtfulAccountsReceivableForeignCurrencyTranslation_39ffaf78-85bb-4a73-b3b5-cd06899c8330" xlink:href="pwp-20221231.xsd#pwp_AllowanceForDoubtfulAccountsReceivableForeignCurrencyTranslation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableRollforward_b5d90b17-54fe-4067-af17-94ae4b2d5052" xlink:to="loc_pwp_AllowanceForDoubtfulAccountsReceivableForeignCurrencyTranslation_39ffaf78-85bb-4a73-b3b5-cd06899c8330" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllowanceForDoubtfulAccountsReceivable_96094412-58e4-4672-8cb6-b2c590093235" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivable"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_2b71fa12-61e9-42c2-942c-76c15a21ba2a" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_886e46e4-5123-4ddd-a503-94d94912f8b1" xlink:to="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_2b71fa12-61e9-42c2-942c-76c15a21ba2a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_ccd2326d-2c26-44c5-bed8-803b3abea8d3" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AdjustmentsForNewAccountingPronouncementsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_2b71fa12-61e9-42c2-942c-76c15a21ba2a" xlink:to="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_ccd2326d-2c26-44c5-bed8-803b3abea8d3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfAdoptionMember_ccd2326d-2c26-44c5-bed8-803b3abea8d3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TypeOfAdoptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_ccd2326d-2c26-44c5-bed8-803b3abea8d3" xlink:to="loc_us-gaap_TypeOfAdoptionMember_ccd2326d-2c26-44c5-bed8-803b3abea8d3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfAdoptionMember_44686acf-eeec-4d5f-9117-96310118e6b8" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TypeOfAdoptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_ccd2326d-2c26-44c5-bed8-803b3abea8d3" xlink:to="loc_us-gaap_TypeOfAdoptionMember_44686acf-eeec-4d5f-9117-96310118e6b8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountingStandardsUpdate201613Member_b284ff98-2101-4bb7-9abe-e1901afc0a93" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AccountingStandardsUpdate201613Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfAdoptionMember_44686acf-eeec-4d5f-9117-96310118e6b8" xlink:to="loc_us-gaap_AccountingStandardsUpdate201613Member_b284ff98-2101-4bb7-9abe-e1901afc0a93" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pwp.com/role/RevenueandReceivablesfromContractswithCustomersScheduleofAllowanceforCreditLossesNarrativeDetails" xlink:type="simple" xlink:href="pwp-20221231.xsd#RevenueandReceivablesfromContractswithCustomersScheduleofAllowanceforCreditLossesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://pwp.com/role/RevenueandReceivablesfromContractswithCustomersScheduleofAllowanceforCreditLossesNarrativeDetails" xlink:type="extended" id="i5659244daa69497c96424ddbfc47e91e_RevenueandReceivablesfromContractswithCustomersScheduleofAllowanceforCreditLossesNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems_c7f0c62c-b204-4b33-9463-e49c008025e1" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesPeriodIncreaseDecrease_7170860e-3e17-4d9d-803a-e3f17923fd03" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FinancingReceivableAllowanceForCreditLossesPeriodIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems_c7f0c62c-b204-4b33-9463-e49c008025e1" xlink:to="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesPeriodIncreaseDecrease_7170860e-3e17-4d9d-803a-e3f17923fd03" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFinancingReceivableAllowanceForCreditLossesTable_8e13ecc8-5b6f-4ea3-9477-402ca0c4b0ad" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfFinancingReceivableAllowanceForCreditLossesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems_c7f0c62c-b204-4b33-9463-e49c008025e1" xlink:to="loc_us-gaap_ScheduleOfFinancingReceivableAllowanceForCreditLossesTable_8e13ecc8-5b6f-4ea3-9477-402ca0c4b0ad" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_c83725de-e449-44ce-a5be-3b051a9b1fbd" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AdjustmentsForNewAccountingPronouncementsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivableAllowanceForCreditLossesTable_8e13ecc8-5b6f-4ea3-9477-402ca0c4b0ad" xlink:to="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_c83725de-e449-44ce-a5be-3b051a9b1fbd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfAdoptionMember_c83725de-e449-44ce-a5be-3b051a9b1fbd_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TypeOfAdoptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_c83725de-e449-44ce-a5be-3b051a9b1fbd" xlink:to="loc_us-gaap_TypeOfAdoptionMember_c83725de-e449-44ce-a5be-3b051a9b1fbd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfAdoptionMember_e495d334-0037-4fa1-bef7-a9dd1195951f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TypeOfAdoptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_c83725de-e449-44ce-a5be-3b051a9b1fbd" xlink:to="loc_us-gaap_TypeOfAdoptionMember_e495d334-0037-4fa1-bef7-a9dd1195951f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountingStandardsUpdate201613Member_943eefce-2d86-4230-9536-e9c4f78570fd" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AccountingStandardsUpdate201613Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfAdoptionMember_e495d334-0037-4fa1-bef7-a9dd1195951f" xlink:to="loc_us-gaap_AccountingStandardsUpdate201613Member_943eefce-2d86-4230-9536-e9c4f78570fd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_4c735768-7f5f-40dc-88ed-4c79589f78f9" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_CumulativeEffectPeriodOfAdoptionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivableAllowanceForCreditLossesTable_8e13ecc8-5b6f-4ea3-9477-402ca0c4b0ad" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_4c735768-7f5f-40dc-88ed-4c79589f78f9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_4c735768-7f5f-40dc-88ed-4c79589f78f9_default" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_CumulativeEffectPeriodOfAdoptionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_4c735768-7f5f-40dc-88ed-4c79589f78f9" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_4c735768-7f5f-40dc-88ed-4c79589f78f9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_1f89d6c6-b928-46f8-9e25-c3626c8298cf" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_CumulativeEffectPeriodOfAdoptionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_4c735768-7f5f-40dc-88ed-4c79589f78f9" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_1f89d6c6-b928-46f8-9e25-c3626c8298cf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember_94f41587-0d88-4493-bb16-e95af6e4b60b" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_1f89d6c6-b928-46f8-9e25-c3626c8298cf" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember_94f41587-0d88-4493-bb16-e95af6e4b60b" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pwp.com/role/LeasesAdditionalInformationDetails" xlink:type="simple" xlink:href="pwp-20221231.xsd#LeasesAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://pwp.com/role/LeasesAdditionalInformationDetails" xlink:type="extended" id="i7ce43fcfbb3d48fdb9fe17f7beabc962_LeasesAdditionalInformationDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionLineItems_5bf7219f-67c3-42ca-9102-8f7b34a70ce6" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LesseeLeaseDescriptionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInOperatingLeaseLiability_bba034c8-1749-4c91-bd67-6877baa4bc31" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncreaseDecreaseInOperatingLeaseLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_5bf7219f-67c3-42ca-9102-8f7b34a70ce6" xlink:to="loc_us-gaap_IncreaseDecreaseInOperatingLeaseLiability_bba034c8-1749-4c91-bd67-6877baa4bc31" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability_7eea9e63-7c60-4245-a046-9f4552e6a7fd" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_5bf7219f-67c3-42ca-9102-8f7b34a70ce6" xlink:to="loc_us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability_7eea9e63-7c60-4245-a046-9f4552e6a7fd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_GainLossOnModificationOfLease_50c418c1-e91b-4ef7-bf71-6b02489238de" xlink:href="pwp-20221231.xsd#pwp_GainLossOnModificationOfLease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_5bf7219f-67c3-42ca-9102-8f7b34a70ce6" xlink:to="loc_pwp_GainLossOnModificationOfLease_50c418c1-e91b-4ef7-bf71-6b02489238de" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseRenewalTerm_2483e349-d636-4083-a0f3-755912b3bd42" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LesseeOperatingLeaseRenewalTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_5bf7219f-67c3-42ca-9102-8f7b34a70ce6" xlink:to="loc_us-gaap_LesseeOperatingLeaseRenewalTerm_2483e349-d636-4083-a0f3-755912b3bd42" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_IncreaseDecreaseInOperatingLeaseRightOfUseAsset_5a922ec4-750a-484f-a7c5-e13025db1490" xlink:href="pwp-20221231.xsd#pwp_IncreaseDecreaseInOperatingLeaseRightOfUseAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_5bf7219f-67c3-42ca-9102-8f7b34a70ce6" xlink:to="loc_pwp_IncreaseDecreaseInOperatingLeaseRightOfUseAsset_5a922ec4-750a-484f-a7c5-e13025db1490" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnTerminationOfLease_ef2767ae-5e9f-4862-99d7-7e923ccc0b75" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_GainLossOnTerminationOfLease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_5bf7219f-67c3-42ca-9102-8f7b34a70ce6" xlink:to="loc_us-gaap_GainLossOnTerminationOfLease_ef2767ae-5e9f-4862-99d7-7e923ccc0b75" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionTable_100491aa-25c0-4c9e-ba9c-5e6e6045984b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LesseeLeaseDescriptionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_5bf7219f-67c3-42ca-9102-8f7b34a70ce6" xlink:to="loc_us-gaap_LesseeLeaseDescriptionTable_100491aa-25c0-4c9e-ba9c-5e6e6045984b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_f41b8dbb-1f91-455c-8d32-b4cf31f2addf" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_100491aa-25c0-4c9e-ba9c-5e6e6045984b" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_f41b8dbb-1f91-455c-8d32-b4cf31f2addf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_f41b8dbb-1f91-455c-8d32-b4cf31f2addf_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_f41b8dbb-1f91-455c-8d32-b4cf31f2addf" xlink:to="loc_us-gaap_SegmentDomain_f41b8dbb-1f91-455c-8d32-b4cf31f2addf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_96b29d4d-4617-41ad-8232-9495507963e7" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_f41b8dbb-1f91-455c-8d32-b4cf31f2addf" xlink:to="loc_us-gaap_SegmentDomain_96b29d4d-4617-41ad-8232-9495507963e7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_NewYorkOfficeMember_0ac37d5a-4481-4bfa-8059-216fe1813c3f" xlink:href="pwp-20221231.xsd#pwp_NewYorkOfficeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_96b29d4d-4617-41ad-8232-9495507963e7" xlink:to="loc_pwp_NewYorkOfficeMember_0ac37d5a-4481-4bfa-8059-216fe1813c3f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_HoustonOfficeMember_e2e3e8c8-ef47-4355-87b0-5098d1ef6bce" xlink:href="pwp-20221231.xsd#pwp_HoustonOfficeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_96b29d4d-4617-41ad-8232-9495507963e7" xlink:to="loc_pwp_HoustonOfficeMember_e2e3e8c8-ef47-4355-87b0-5098d1ef6bce" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_4d93c585-2500-4967-a8e7-79f0a5c8843b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_100491aa-25c0-4c9e-ba9c-5e6e6045984b" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_4d93c585-2500-4967-a8e7-79f0a5c8843b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_4d93c585-2500-4967-a8e7-79f0a5c8843b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_4d93c585-2500-4967-a8e7-79f0a5c8843b" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_4d93c585-2500-4967-a8e7-79f0a5c8843b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_1082db43-e2a8-4e82-98ee-efa1a6de56e4" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_4d93c585-2500-4967-a8e7-79f0a5c8843b" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_1082db43-e2a8-4e82-98ee-efa1a6de56e4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_LosAngelesAndNewYorkOfficeMember_e8ad89a8-5be4-4530-a9d0-3a2894abf617" xlink:href="pwp-20221231.xsd#pwp_LosAngelesAndNewYorkOfficeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_1082db43-e2a8-4e82-98ee-efa1a6de56e4" xlink:to="loc_pwp_LosAngelesAndNewYorkOfficeMember_e8ad89a8-5be4-4530-a9d0-3a2894abf617" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_LondonAndNewYorkOfficeMember_6663048a-dd86-4b66-b7fc-cf9c69e44176" xlink:href="pwp-20221231.xsd#pwp_LondonAndNewYorkOfficeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_1082db43-e2a8-4e82-98ee-efa1a6de56e4" xlink:to="loc_pwp_LondonAndNewYorkOfficeMember_6663048a-dd86-4b66-b7fc-cf9c69e44176" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_NewYorkOfficeMember_02b6aa1f-d7b8-4191-85e7-087fb93ff2ca" xlink:href="pwp-20221231.xsd#pwp_NewYorkOfficeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_1082db43-e2a8-4e82-98ee-efa1a6de56e4" xlink:to="loc_pwp_NewYorkOfficeMember_02b6aa1f-d7b8-4191-85e7-087fb93ff2ca" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_HoustonOfficeMember_f21d8c73-feb4-41a6-8c88-b1e941ba63dd" xlink:href="pwp-20221231.xsd#pwp_HoustonOfficeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_1082db43-e2a8-4e82-98ee-efa1a6de56e4" xlink:to="loc_pwp_HoustonOfficeMember_f21d8c73-feb4-41a6-8c88-b1e941ba63dd" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_LondonOfficeMember_65a0ccfc-5c61-4cc1-9325-79bbf246ffbe" xlink:href="pwp-20221231.xsd#pwp_LondonOfficeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_1082db43-e2a8-4e82-98ee-efa1a6de56e4" xlink:to="loc_pwp_LondonOfficeMember_65a0ccfc-5c61-4cc1-9325-79bbf246ffbe" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pwp.com/role/GoodwillandIntangibleAssetsAdditionalInformationDetails" xlink:type="simple" xlink:href="pwp-20221231.xsd#GoodwillandIntangibleAssetsAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://pwp.com/role/GoodwillandIntangibleAssetsAdditionalInformationDetails" xlink:type="extended" id="i415e21150bda46c8b7aab6fb4c2d9d31_GoodwillandIntangibleAssetsAdditionalInformationDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillLineItems_6ab80a16-2367-49c8-b7bc-712aa2addf05" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_GoodwillLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillAcquiredDuringPeriod_06400d18-250d-4a02-8887-a6738afe9f3c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_GoodwillAcquiredDuringPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_6ab80a16-2367-49c8-b7bc-712aa2addf05" xlink:to="loc_us-gaap_GoodwillAcquiredDuringPeriod_06400d18-250d-4a02-8887-a6738afe9f3c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillImpairmentLoss_fc725697-cf9c-4ed3-8416-7060aa7cdf07" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_GoodwillImpairmentLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_6ab80a16-2367-49c8-b7bc-712aa2addf05" xlink:to="loc_us-gaap_GoodwillImpairmentLoss_fc725697-cf9c-4ed3-8416-7060aa7cdf07" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfGoodwillTable_2f7dbd52-3bbb-4146-85ab-e8ca8b242647" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfGoodwillTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_GoodwillLineItems_6ab80a16-2367-49c8-b7bc-712aa2addf05" xlink:to="loc_us-gaap_ScheduleOfGoodwillTable_2f7dbd52-3bbb-4146-85ab-e8ca8b242647" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_ee5e7378-02dd-4208-903d-9a3c87bab9f7" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_2f7dbd52-3bbb-4146-85ab-e8ca8b242647" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_ee5e7378-02dd-4208-903d-9a3c87bab9f7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_ee5e7378-02dd-4208-903d-9a3c87bab9f7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_ee5e7378-02dd-4208-903d-9a3c87bab9f7" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_ee5e7378-02dd-4208-903d-9a3c87bab9f7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_75446d78-0b66-4545-b9a5-2090c5b4fbc4" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_ee5e7378-02dd-4208-903d-9a3c87bab9f7" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_75446d78-0b66-4545-b9a5-2090c5b4fbc4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_TudorPickeringHoltCoLLCMember_d10a15f4-4eda-40d8-8303-2435d0ac5e58" xlink:href="pwp-20221231.xsd#pwp_TudorPickeringHoltCoLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_75446d78-0b66-4545-b9a5-2090c5b4fbc4" xlink:to="loc_pwp_TudorPickeringHoltCoLLCMember_d10a15f4-4eda-40d8-8303-2435d0ac5e58" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pwp.com/role/GoodwillandIntangibleAssetsSummaryofComponentsofGrossandNetIntangibleAssetDetails" xlink:type="simple" xlink:href="pwp-20221231.xsd#GoodwillandIntangibleAssetsSummaryofComponentsofGrossandNetIntangibleAssetDetails"/>
  <link:definitionLink xlink:role="http://pwp.com/role/GoodwillandIntangibleAssetsSummaryofComponentsofGrossandNetIntangibleAssetDetails" xlink:type="extended" id="i1ec43138492741939e3bcd69ffbe8fbb_GoodwillandIntangibleAssetsSummaryofComponentsofGrossandNetIntangibleAssetDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_ad1a7bad-e211-4273-92f6-fe27d1d85e54" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_dcdaa3ae-b0d9-479c-b86e-edb2c3209abc" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FiniteLivedIntangibleAssetsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_ad1a7bad-e211-4273-92f6-fe27d1d85e54" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_dcdaa3ae-b0d9-479c-b86e-edb2c3209abc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_cf4ddf33-9376-43dd-8d32-52ebb98fbd70" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_ad1a7bad-e211-4273-92f6-fe27d1d85e54" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_cf4ddf33-9376-43dd-8d32-52ebb98fbd70" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_14bc1e95-8dc2-4b9b-90e7-697fcf0ede70" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FiniteLivedIntangibleAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_ad1a7bad-e211-4273-92f6-fe27d1d85e54" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNet_14bc1e95-8dc2-4b9b-90e7-697fcf0ede70" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_a293b3d5-4eac-4b2a-85b8-7620582f161e" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_ad1a7bad-e211-4273-92f6-fe27d1d85e54" xlink:to="loc_us-gaap_StatementTable_a293b3d5-4eac-4b2a-85b8-7620582f161e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_99170a23-e5ea-43ec-9970-236fe80a6da6" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_a293b3d5-4eac-4b2a-85b8-7620582f161e" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_99170a23-e5ea-43ec-9970-236fe80a6da6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_99170a23-e5ea-43ec-9970-236fe80a6da6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_99170a23-e5ea-43ec-9970-236fe80a6da6" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_99170a23-e5ea-43ec-9970-236fe80a6da6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_8e7c822b-9b13-4b93-bd3b-2d39178c2493" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_99170a23-e5ea-43ec-9970-236fe80a6da6" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_8e7c822b-9b13-4b93-bd3b-2d39178c2493" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_689b3bbb-6553-4112-b091-880e9bd1bb1c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_8e7c822b-9b13-4b93-bd3b-2d39178c2493" xlink:to="loc_us-gaap_CustomerRelationshipsMember_689b3bbb-6553-4112-b091-880e9bd1bb1c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TrademarksAndTradeNamesMember_bd4f6dea-7130-485e-9880-cb77e8db27ce" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TrademarksAndTradeNamesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_8e7c822b-9b13-4b93-bd3b-2d39178c2493" xlink:to="loc_us-gaap_TrademarksAndTradeNamesMember_bd4f6dea-7130-485e-9880-cb77e8db27ce" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pwp.com/role/FixedAssetsSummaryofFixedAssetsDetails" xlink:type="simple" xlink:href="pwp-20221231.xsd#FixedAssetsSummaryofFixedAssetsDetails"/>
  <link:definitionLink xlink:role="http://pwp.com/role/FixedAssetsSummaryofFixedAssetsDetails" xlink:type="extended" id="i683a7646cad04bcb9db021ce64095d57_FixedAssetsSummaryofFixedAssetsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_5b9a2560-1a1a-40e7-bff4-78fecaecd295" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_6d31688b-ac4e-4377-a7b1-ab694bd39fbb" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_5b9a2560-1a1a-40e7-bff4-78fecaecd295" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_6d31688b-ac4e-4377-a7b1-ab694bd39fbb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_d5e9e987-3794-4363-9584-33c43a205287" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_5b9a2560-1a1a-40e7-bff4-78fecaecd295" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_d5e9e987-3794-4363-9584-33c43a205287" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_f7ea0b03-162f-4e2d-90d1-a4dc52aefe3c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_5b9a2560-1a1a-40e7-bff4-78fecaecd295" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_f7ea0b03-162f-4e2d-90d1-a4dc52aefe3c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_483af182-7b45-476e-818d-7e8d09ad1f19" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_5b9a2560-1a1a-40e7-bff4-78fecaecd295" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_483af182-7b45-476e-818d-7e8d09ad1f19" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_e2385a2d-d777-4a17-b86e-75dfbb232727" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_483af182-7b45-476e-818d-7e8d09ad1f19" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_e2385a2d-d777-4a17-b86e-75dfbb232727" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_e2385a2d-d777-4a17-b86e-75dfbb232727_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_e2385a2d-d777-4a17-b86e-75dfbb232727" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_e2385a2d-d777-4a17-b86e-75dfbb232727_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_b18c3231-3e04-4a9e-9f7a-086da23b211e" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_e2385a2d-d777-4a17-b86e-75dfbb232727" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_b18c3231-3e04-4a9e-9f7a-086da23b211e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseholdImprovementsMember_0109d099-a44d-431d-b767-ed4e4517c30b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LeaseholdImprovementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_b18c3231-3e04-4a9e-9f7a-086da23b211e" xlink:to="loc_us-gaap_LeaseholdImprovementsMember_0109d099-a44d-431d-b767-ed4e4517c30b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FurnitureAndFixturesMember_2965d4c7-5faa-4656-9d48-5f9b77ac53fb" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FurnitureAndFixturesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_b18c3231-3e04-4a9e-9f7a-086da23b211e" xlink:to="loc_us-gaap_FurnitureAndFixturesMember_2965d4c7-5faa-4656-9d48-5f9b77ac53fb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquipmentMember_3f8c3f22-271a-4ea5-b2d4-23e8bf26c43b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_b18c3231-3e04-4a9e-9f7a-086da23b211e" xlink:to="loc_us-gaap_EquipmentMember_3f8c3f22-271a-4ea5-b2d4-23e8bf26c43b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_SoftwareMember_f70e13c5-b286-4851-9024-b8843fc80b64" xlink:href="pwp-20221231.xsd#pwp_SoftwareMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_b18c3231-3e04-4a9e-9f7a-086da23b211e" xlink:to="loc_pwp_SoftwareMember_f70e13c5-b286-4851-9024-b8843fc80b64" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pwp.com/role/FixedAssetsAdditionalinformationDetails" xlink:type="simple" xlink:href="pwp-20221231.xsd#FixedAssetsAdditionalinformationDetails"/>
  <link:definitionLink xlink:role="http://pwp.com/role/FixedAssetsAdditionalinformationDetails" xlink:type="extended" id="i6137bb801bc044e3931b1ceefce01433_FixedAssetsAdditionalinformationDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_727a1649-7dc1-40b4-be5c-9b380ab79cf1" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Depreciation_f8709c6e-0ab8-4afe-9f39-cbb8a6be7ab0" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_Depreciation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_727a1649-7dc1-40b4-be5c-9b380ab79cf1" xlink:to="loc_us-gaap_Depreciation_f8709c6e-0ab8-4afe-9f39-cbb8a6be7ab0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentForAmortization_b92e6da1-d8a3-4c2a-8eb8-863c6bbffa6a" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AdjustmentForAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_727a1649-7dc1-40b4-be5c-9b380ab79cf1" xlink:to="loc_us-gaap_AdjustmentForAmortization_b92e6da1-d8a3-4c2a-8eb8-863c6bbffa6a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_926c0c78-2212-4aa5-9cdd-4cb40d47802b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_727a1649-7dc1-40b4-be5c-9b380ab79cf1" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_926c0c78-2212-4aa5-9cdd-4cb40d47802b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_2470ec12-d0be-4012-89b5-2e82ed1c17f4" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_926c0c78-2212-4aa5-9cdd-4cb40d47802b" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_2470ec12-d0be-4012-89b5-2e82ed1c17f4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_2470ec12-d0be-4012-89b5-2e82ed1c17f4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_2470ec12-d0be-4012-89b5-2e82ed1c17f4" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_2470ec12-d0be-4012-89b5-2e82ed1c17f4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_4896a905-275b-4878-a258-0f75c8331805" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_2470ec12-d0be-4012-89b5-2e82ed1c17f4" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_4896a905-275b-4878-a258-0f75c8331805" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SoftwareDevelopmentMember_07f890a9-1e75-4f90-921e-2613289670b1" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SoftwareDevelopmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_4896a905-275b-4878-a258-0f75c8331805" xlink:to="loc_us-gaap_SoftwareDevelopmentMember_07f890a9-1e75-4f90-921e-2613289670b1" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pwp.com/role/DebtNarrativeDetails" xlink:type="simple" xlink:href="pwp-20221231.xsd#DebtNarrativeDetails"/>
  <link:definitionLink xlink:role="http://pwp.com/role/DebtNarrativeDetails" xlink:type="extended" id="ie3af34d56cf443b5bebdfce713cf31a0_DebtNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_2b374a9d-086c-4bdc-aa65-9c7eec59d97f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_b7b7013f-8f8d-472d-a1a3-a630de0880bd" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2b374a9d-086c-4bdc-aa65-9c7eec59d97f" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_b7b7013f-8f8d-472d-a1a3-a630de0880bd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfLinesOfCredit_fe64b05b-aa61-4456-9914-1ed3be51eecc" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RepaymentsOfLinesOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2b374a9d-086c-4bdc-aa65-9c7eec59d97f" xlink:to="loc_us-gaap_RepaymentsOfLinesOfCredit_fe64b05b-aa61-4456-9914-1ed3be51eecc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_8f081790-096e-48fe-8ef6-170331ffce73" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2b374a9d-086c-4bdc-aa65-9c7eec59d97f" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_8f081790-096e-48fe-8ef6-170331ffce73" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityCommitmentFeePercentage_1491e5e7-ca64-4227-ada6-b395c12e3e1c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LineOfCreditFacilityCommitmentFeePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2b374a9d-086c-4bdc-aa65-9c7eec59d97f" xlink:to="loc_us-gaap_LineOfCreditFacilityCommitmentFeePercentage_1491e5e7-ca64-4227-ada6-b395c12e3e1c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_MaximumAmountOfRevolvingCreditFacilityForLettersOfCredit_b52db76e-1ff9-4899-aaf9-f7c32410ca45" xlink:href="pwp-20221231.xsd#pwp_MaximumAmountOfRevolvingCreditFacilityForLettersOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2b374a9d-086c-4bdc-aa65-9c7eec59d97f" xlink:to="loc_pwp_MaximumAmountOfRevolvingCreditFacilityForLettersOfCredit_b52db76e-1ff9-4899-aaf9-f7c32410ca45" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_MaximumIncrementalRevolvingCommitments_fc2b035c-9352-4f74-a198-be091984761a" xlink:href="pwp-20221231.xsd#pwp_MaximumIncrementalRevolvingCommitments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2b374a9d-086c-4bdc-aa65-9c7eec59d97f" xlink:to="loc_pwp_MaximumIncrementalRevolvingCommitments_fc2b035c-9352-4f74-a198-be091984761a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateDuringPeriod_2f5b89b7-51c8-4bb4-920d-5c3da4947d53" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentInterestRateDuringPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2b374a9d-086c-4bdc-aa65-9c7eec59d97f" xlink:to="loc_us-gaap_DebtInstrumentInterestRateDuringPeriod_2f5b89b7-51c8-4bb4-920d-5c3da4947d53" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFinanceCostsGross_d8177ee5-d7f2-49ec-87b0-1b0dd9356c0f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DeferredFinanceCostsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2b374a9d-086c-4bdc-aa65-9c7eec59d97f" xlink:to="loc_us-gaap_DeferredFinanceCostsGross_d8177ee5-d7f2-49ec-87b0-1b0dd9356c0f" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfDebtRestructuringCosts_c8391a19-ace2-4b0a-aa8f-48ceff87dc4f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PaymentsOfDebtRestructuringCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2b374a9d-086c-4bdc-aa65-9c7eec59d97f" xlink:to="loc_us-gaap_PaymentsOfDebtRestructuringCosts_c8391a19-ace2-4b0a-aa8f-48ceff87dc4f" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCredit_781b3bd4-3395-4aa9-a82e-01cb5513c3a8" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LineOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2b374a9d-086c-4bdc-aa65-9c7eec59d97f" xlink:to="loc_us-gaap_LineOfCredit_781b3bd4-3395-4aa9-a82e-01cb5513c3a8" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseDebt_14a7bcf6-7e70-4aeb-a0f2-902bee9454c2" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_InterestExpenseDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2b374a9d-086c-4bdc-aa65-9c7eec59d97f" xlink:to="loc_us-gaap_InterestExpenseDebt_14a7bcf6-7e70-4aeb-a0f2-902bee9454c2" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_0677299d-8146-49d9-85d3-3c8de614791f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2b374a9d-086c-4bdc-aa65-9c7eec59d97f" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_0677299d-8146-49d9-85d3-3c8de614791f" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_0a9dd1ca-d2e1-4eea-a6e1-87fa51079560" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2b374a9d-086c-4bdc-aa65-9c7eec59d97f" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_0a9dd1ca-d2e1-4eea-a6e1-87fa51079560" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentConvertibleBeneficialConversionFeature_5c6b04cc-3369-4ead-9309-42ee087aac8e" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentConvertibleBeneficialConversionFeature"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2b374a9d-086c-4bdc-aa65-9c7eec59d97f" xlink:to="loc_us-gaap_DebtInstrumentConvertibleBeneficialConversionFeature_5c6b04cc-3369-4ead-9309-42ee087aac8e" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRepurchaseAmount_8e5b36d9-a218-4def-a27d-5723361f6c02" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentRepurchaseAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2b374a9d-086c-4bdc-aa65-9c7eec59d97f" xlink:to="loc_us-gaap_DebtInstrumentRepurchaseAmount_8e5b36d9-a218-4def-a27d-5723361f6c02" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRepurchasedFaceAmount_95a6140c-a2d9-45ee-b864-f52641f70171" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentRepurchasedFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2b374a9d-086c-4bdc-aa65-9c7eec59d97f" xlink:to="loc_us-gaap_DebtInstrumentRepurchasedFaceAmount_95a6140c-a2d9-45ee-b864-f52641f70171" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_MinimumAmountHeldByRedeemingHolders_792b88a5-e123-4fae-a255-3812cb408412" xlink:href="pwp-20221231.xsd#pwp_MinimumAmountHeldByRedeemingHolders"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2b374a9d-086c-4bdc-aa65-9c7eec59d97f" xlink:to="loc_pwp_MinimumAmountHeldByRedeemingHolders_792b88a5-e123-4fae-a255-3812cb408412" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_86f68f92-355b-4e98-bcba-1400270bad90" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2b374a9d-086c-4bdc-aa65-9c7eec59d97f" xlink:to="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_86f68f92-355b-4e98-bcba-1400270bad90" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_PremiumPaidToCertainRedeemingHolders_8636811e-9987-447c-a30b-3dbb9072a25f" xlink:href="pwp-20221231.xsd#pwp_PremiumPaidToCertainRedeemingHolders"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2b374a9d-086c-4bdc-aa65-9c7eec59d97f" xlink:to="loc_pwp_PremiumPaidToCertainRedeemingHolders_8636811e-9987-447c-a30b-3dbb9072a25f" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_51dbeae2-7d25-4d9a-9265-f1a3b7369519" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2b374a9d-086c-4bdc-aa65-9c7eec59d97f" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_51dbeae2-7d25-4d9a-9265-f1a3b7369519" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtWeightedAverageInterestRateOverTime_ad80f798-3b31-4350-90f1-02fb7ccb9f4c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LongTermDebtWeightedAverageInterestRateOverTime"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2b374a9d-086c-4bdc-aa65-9c7eec59d97f" xlink:to="loc_us-gaap_LongTermDebtWeightedAverageInterestRateOverTime_ad80f798-3b31-4350-90f1-02fb7ccb9f4c" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_4bf89433-3f94-48e6-9673-5e170f673095" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2b374a9d-086c-4bdc-aa65-9c7eec59d97f" xlink:to="loc_us-gaap_DebtInstrumentTable_4bf89433-3f94-48e6-9673-5e170f673095" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_29559d5b-4c0c-442f-9b60-55624a85ed0b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_4bf89433-3f94-48e6-9673-5e170f673095" xlink:to="loc_us-gaap_CreditFacilityAxis_29559d5b-4c0c-442f-9b60-55624a85ed0b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_29559d5b-4c0c-442f-9b60-55624a85ed0b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_29559d5b-4c0c-442f-9b60-55624a85ed0b" xlink:to="loc_us-gaap_CreditFacilityDomain_29559d5b-4c0c-442f-9b60-55624a85ed0b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_a84dd656-a4aa-444b-ab2d-b9bf53b5c699" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_29559d5b-4c0c-442f-9b60-55624a85ed0b" xlink:to="loc_us-gaap_CreditFacilityDomain_a84dd656-a4aa-444b-ab2d-b9bf53b5c699" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_33caceb6-ed54-48c7-82f8-e39268c67619" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_a84dd656-a4aa-444b-ab2d-b9bf53b5c699" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_33caceb6-ed54-48c7-82f8-e39268c67619" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_b5fc4f51-2d98-4b2f-b99a-a74bee0f6ed6" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_4bf89433-3f94-48e6-9673-5e170f673095" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_b5fc4f51-2d98-4b2f-b99a-a74bee0f6ed6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_b5fc4f51-2d98-4b2f-b99a-a74bee0f6ed6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_b5fc4f51-2d98-4b2f-b99a-a74bee0f6ed6" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_b5fc4f51-2d98-4b2f-b99a-a74bee0f6ed6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_1707209c-20b5-4cb7-bfca-dfefbaea4a51" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_b5fc4f51-2d98-4b2f-b99a-a74bee0f6ed6" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_1707209c-20b5-4cb7-bfca-dfefbaea4a51" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConvertibleDebtMember_b3ab10b6-af3b-4753-ae47-6ba9ba142112" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ConvertibleDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_1707209c-20b5-4cb7-bfca-dfefbaea4a51" xlink:to="loc_us-gaap_ConvertibleDebtMember_b3ab10b6-af3b-4753-ae47-6ba9ba142112" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateAxis_6809e9e5-30f9-459e-935b-8c3065d78a68" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_VariableRateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_4bf89433-3f94-48e6-9673-5e170f673095" xlink:to="loc_us-gaap_VariableRateAxis_6809e9e5-30f9-459e-935b-8c3065d78a68" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_6809e9e5-30f9-459e-935b-8c3065d78a68_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_6809e9e5-30f9-459e-935b-8c3065d78a68" xlink:to="loc_us-gaap_VariableRateDomain_6809e9e5-30f9-459e-935b-8c3065d78a68_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_b74066ec-98f3-4662-80e5-a9acf5f575aa" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_6809e9e5-30f9-459e-935b-8c3065d78a68" xlink:to="loc_us-gaap_VariableRateDomain_b74066ec-98f3-4662-80e5-a9acf5f575aa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_FixedRateMember_e1bdbfb9-5c81-476c-8e9a-ff07b98b77c6" xlink:href="pwp-20221231.xsd#pwp_FixedRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_b74066ec-98f3-4662-80e5-a9acf5f575aa" xlink:to="loc_pwp_FixedRateMember_e1bdbfb9-5c81-476c-8e9a-ff07b98b77c6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_3b6a3d52-24bd-4f3b-b453-b87a7b1230b1" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LondonInterbankOfferedRateLIBORMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_b74066ec-98f3-4662-80e5-a9acf5f575aa" xlink:to="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_3b6a3d52-24bd-4f3b-b453-b87a7b1230b1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_CadenceBankPrimeRateMember_9814b5e7-4238-440c-8099-cfa9d629434a" xlink:href="pwp-20221231.xsd#pwp_CadenceBankPrimeRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_b74066ec-98f3-4662-80e5-a9acf5f575aa" xlink:to="loc_pwp_CadenceBankPrimeRateMember_9814b5e7-4238-440c-8099-cfa9d629434a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_EffectiveInterestRateMember_16410732-9f6c-47ed-aca1-32e7ded99ae1" xlink:href="pwp-20221231.xsd#pwp_EffectiveInterestRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_b74066ec-98f3-4662-80e5-a9acf5f575aa" xlink:to="loc_pwp_EffectiveInterestRateMember_16410732-9f6c-47ed-aca1-32e7ded99ae1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_67f05172-be63-4397-90a2-68f99abeb6b6" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_4bf89433-3f94-48e6-9673-5e170f673095" xlink:to="loc_srt_RangeAxis_67f05172-be63-4397-90a2-68f99abeb6b6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_67f05172-be63-4397-90a2-68f99abeb6b6_default" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_67f05172-be63-4397-90a2-68f99abeb6b6" xlink:to="loc_srt_RangeMember_67f05172-be63-4397-90a2-68f99abeb6b6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_1a413313-f032-4134-bf80-e69a342f0a88" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_67f05172-be63-4397-90a2-68f99abeb6b6" xlink:to="loc_srt_RangeMember_1a413313-f032-4134-bf80-e69a342f0a88" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_b9c801fe-4e8e-4f4c-a1ac-a4d4f0509e05" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_1a413313-f032-4134-bf80-e69a342f0a88" xlink:to="loc_srt_MinimumMember_b9c801fe-4e8e-4f4c-a1ac-a4d4f0509e05" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pwp.com/role/StockholdersEquityAdditionalInformationDetails" xlink:type="simple" xlink:href="pwp-20221231.xsd#StockholdersEquityAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://pwp.com/role/StockholdersEquityAdditionalInformationDetails" xlink:type="extended" id="i3753c32ec0c5492aa97aaaa8614a9820_StockholdersEquityAdditionalInformationDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockLineItems_f4c6b3a0-82c0-4a2e-b99a-e549e611935c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfStockLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_CommonStockNumberOfVotingRights_f3024721-1ea8-42ad-896e-b0801ee2e418" xlink:href="pwp-20221231.xsd#pwp_CommonStockNumberOfVotingRights"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_f4c6b3a0-82c0-4a2e-b99a-e549e611935c" xlink:to="loc_pwp_CommonStockNumberOfVotingRights_f3024721-1ea8-42ad-896e-b0801ee2e418" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightOutstanding_1e2279a2-0521-46ed-97ac-ddc32a4b85da" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfWarrantOrRightOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_f4c6b3a0-82c0-4a2e-b99a-e549e611935c" xlink:to="loc_us-gaap_ClassOfWarrantOrRightOutstanding_1e2279a2-0521-46ed-97ac-ddc32a4b85da" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_DistributionRateForClassBCommonStockComparedToClassA_d47860a5-c477-48d3-97bd-18530f0fbe95" xlink:href="pwp-20221231.xsd#pwp_DistributionRateForClassBCommonStockComparedToClassA"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_f4c6b3a0-82c0-4a2e-b99a-e549e611935c" xlink:to="loc_pwp_DistributionRateForClassBCommonStockComparedToClassA_d47860a5-c477-48d3-97bd-18530f0fbe95" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_MinimumPercentageCondition_bd0c7379-2285-406d-945d-997fd8794f88" xlink:href="pwp-20221231.xsd#pwp_MinimumPercentageCondition"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_f4c6b3a0-82c0-4a2e-b99a-e549e611935c" xlink:to="loc_pwp_MinimumPercentageCondition_bd0c7379-2285-406d-945d-997fd8794f88" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_CommonStockNumberOfVotingRightsWithCeasedThresholdPercentage_42387464-04a4-4bd4-9ba8-117b5427674f" xlink:href="pwp-20221231.xsd#pwp_CommonStockNumberOfVotingRightsWithCeasedThresholdPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_f4c6b3a0-82c0-4a2e-b99a-e549e611935c" xlink:to="loc_pwp_CommonStockNumberOfVotingRightsWithCeasedThresholdPercentage_42387464-04a4-4bd4-9ba8-117b5427674f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockDividendsPerShareDeclared_a9618589-df1b-4468-aefa-86a870842e02" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonStockDividendsPerShareDeclared"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_f4c6b3a0-82c0-4a2e-b99a-e549e611935c" xlink:to="loc_us-gaap_CommonStockDividendsPerShareDeclared_a9618589-df1b-4468-aefa-86a870842e02" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Dividends_b4907100-2642-4599-8d01-a0a4481ecfa4" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_Dividends"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_f4c6b3a0-82c0-4a2e-b99a-e549e611935c" xlink:to="loc_us-gaap_Dividends_b4907100-2642-4599-8d01-a0a4481ecfa4" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_DividendsAndDistributionsRate_149c10cb-c046-470e-9d21-6e930e211057" xlink:href="pwp-20221231.xsd#pwp_DividendsAndDistributionsRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_f4c6b3a0-82c0-4a2e-b99a-e549e611935c" xlink:to="loc_pwp_DividendsAndDistributionsRate_149c10cb-c046-470e-9d21-6e930e211057" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchaseProgramAuthorizedAmount1_5716c8c4-0985-450b-92fd-28b7a5226ea2" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockRepurchaseProgramAuthorizedAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_f4c6b3a0-82c0-4a2e-b99a-e549e611935c" xlink:to="loc_us-gaap_StockRepurchaseProgramAuthorizedAmount1_5716c8c4-0985-450b-92fd-28b7a5226ea2" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockSharesAcquired_8224affa-76eb-4d6d-bb63-e39c42f141a6" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TreasuryStockSharesAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_f4c6b3a0-82c0-4a2e-b99a-e549e611935c" xlink:to="loc_us-gaap_TreasuryStockSharesAcquired_8224affa-76eb-4d6d-bb63-e39c42f141a6" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockAcquiredAverageCostPerShare_1a79d993-5ee8-4695-b2cb-283612c7163c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TreasuryStockAcquiredAverageCostPerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_f4c6b3a0-82c0-4a2e-b99a-e549e611935c" xlink:to="loc_us-gaap_TreasuryStockAcquiredAverageCostPerShare_1a79d993-5ee8-4695-b2cb-283612c7163c" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_e1d886ce-9bf6-4f7a-a9d7-a24121ad9e7a" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TreasuryStockValueAcquiredCostMethod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_f4c6b3a0-82c0-4a2e-b99a-e549e611935c" xlink:to="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_e1d886ce-9bf6-4f7a-a9d7-a24121ad9e7a" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_UnitsOfMinorityInterestAmount_8a548ec3-b6b9-4707-a938-33b03cad44b7" xlink:href="pwp-20221231.xsd#pwp_UnitsOfMinorityInterestAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_f4c6b3a0-82c0-4a2e-b99a-e549e611935c" xlink:to="loc_pwp_UnitsOfMinorityInterestAmount_8a548ec3-b6b9-4707-a938-33b03cad44b7" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners_80cf8110-357f-44ae-844e-d51d417a735b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_f4c6b3a0-82c0-4a2e-b99a-e549e611935c" xlink:to="loc_us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners_80cf8110-357f-44ae-844e-d51d417a735b" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_NumberOfFounderShares_74f66ac0-9191-40fe-834c-e59f29e4f65d" xlink:href="pwp-20221231.xsd#pwp_NumberOfFounderShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_f4c6b3a0-82c0-4a2e-b99a-e549e611935c" xlink:to="loc_pwp_NumberOfFounderShares_74f66ac0-9191-40fe-834c-e59f29e4f65d" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_LockUpPeriod_1d9897fa-2b2a-480e-aced-b88ff5052bbc" xlink:href="pwp-20221231.xsd#pwp_LockUpPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_f4c6b3a0-82c0-4a2e-b99a-e549e611935c" xlink:to="loc_pwp_LockUpPeriod_1d9897fa-2b2a-480e-aced-b88ff5052bbc" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_NumberOfSponsorSharesDistributed_d7a6584a-50b7-4a5a-9043-c7c3e377af89" xlink:href="pwp-20221231.xsd#pwp_NumberOfSponsorSharesDistributed"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_f4c6b3a0-82c0-4a2e-b99a-e549e611935c" xlink:to="loc_pwp_NumberOfSponsorSharesDistributed_d7a6584a-50b7-4a5a-9043-c7c3e377af89" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_NumberOfSponsorSharesDistributedSubjectToTransferRestrictions_98e11d3c-f222-40ff-b704-235adf079e06" xlink:href="pwp-20221231.xsd#pwp_NumberOfSponsorSharesDistributedSubjectToTransferRestrictions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_f4c6b3a0-82c0-4a2e-b99a-e549e611935c" xlink:to="loc_pwp_NumberOfSponsorSharesDistributedSubjectToTransferRestrictions_98e11d3c-f222-40ff-b704-235adf079e06" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_MinimumSharePriceAndPurchasePrice_9d4d8cab-e238-4d0f-aa38-6434042c1d52" xlink:href="pwp-20221231.xsd#pwp_MinimumSharePriceAndPurchasePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_f4c6b3a0-82c0-4a2e-b99a-e549e611935c" xlink:to="loc_pwp_MinimumSharePriceAndPurchasePrice_9d4d8cab-e238-4d0f-aa38-6434042c1d52" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_FounderSharesConvertibleMinimumConsecutiveTradingDays_25bdcd26-8df7-4835-9f0b-10357ce88628" xlink:href="pwp-20221231.xsd#pwp_FounderSharesConvertibleMinimumConsecutiveTradingDays"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_f4c6b3a0-82c0-4a2e-b99a-e549e611935c" xlink:to="loc_pwp_FounderSharesConvertibleMinimumConsecutiveTradingDays_25bdcd26-8df7-4835-9f0b-10357ce88628" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_FounderSharesConvertibleThresholdConsecutiveTradingDays_7b8b1b32-0195-460c-9301-a7a8514ec6a7" xlink:href="pwp-20221231.xsd#pwp_FounderSharesConvertibleThresholdConsecutiveTradingDays"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_f4c6b3a0-82c0-4a2e-b99a-e549e611935c" xlink:to="loc_pwp_FounderSharesConvertibleThresholdConsecutiveTradingDays_7b8b1b32-0195-460c-9301-a7a8514ec6a7" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_PeriodFounderSharesMayBePurchased_5277a597-b785-4f7f-8cf4-ac5bf74476b6" xlink:href="pwp-20221231.xsd#pwp_PeriodFounderSharesMayBePurchased"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_f4c6b3a0-82c0-4a2e-b99a-e549e611935c" xlink:to="loc_pwp_PeriodFounderSharesMayBePurchased_5277a597-b785-4f7f-8cf4-ac5bf74476b6" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForRepurchaseOfEquity_3855a660-5a01-44a2-9ec4-acb53738b6d0" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PaymentsForRepurchaseOfEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_f4c6b3a0-82c0-4a2e-b99a-e549e611935c" xlink:to="loc_us-gaap_PaymentsForRepurchaseOfEquity_3855a660-5a01-44a2-9ec4-acb53738b6d0" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_StockholderAgreementPercentCondition_fa6b183d-6b72-4cb4-9653-ce0cc7505f71" xlink:href="pwp-20221231.xsd#pwp_StockholderAgreementPercentCondition"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_f4c6b3a0-82c0-4a2e-b99a-e549e611935c" xlink:to="loc_pwp_StockholderAgreementPercentCondition_fa6b183d-6b72-4cb4-9653-ce0cc7505f71" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_StockholdersEquityNoteConversionRatio_cd4033f7-00c7-4c26-a6fa-9162aa7f9111" xlink:href="pwp-20221231.xsd#pwp_StockholdersEquityNoteConversionRatio"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_f4c6b3a0-82c0-4a2e-b99a-e549e611935c" xlink:to="loc_pwp_StockholdersEquityNoteConversionRatio_cd4033f7-00c7-4c26-a6fa-9162aa7f9111" xlink:type="arc" order="24"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_468674f8-cdbc-488a-b21a-611eb23ebd57" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_f4c6b3a0-82c0-4a2e-b99a-e549e611935c" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_468674f8-cdbc-488a-b21a-611eb23ebd57" xlink:type="arc" order="25"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesIssuedPricePerShare_0415edd8-c98f-4e0d-a544-89d0bcbf1d6d" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SharesIssuedPricePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_f4c6b3a0-82c0-4a2e-b99a-e549e611935c" xlink:to="loc_us-gaap_SharesIssuedPricePerShare_0415edd8-c98f-4e0d-a544-89d0bcbf1d6d" xlink:type="arc" order="26"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_50717488-7d9b-4cdc-a9e0-07a580900e80" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_f4c6b3a0-82c0-4a2e-b99a-e549e611935c" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_50717488-7d9b-4cdc-a9e0-07a580900e80" xlink:type="arc" order="27"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_PaymentOfFinancingAndStockIssuanceCostsPricePerShare_6cee1bc8-5ab8-4cbd-abcc-13183f322881" xlink:href="pwp-20221231.xsd#pwp_PaymentOfFinancingAndStockIssuanceCostsPricePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_f4c6b3a0-82c0-4a2e-b99a-e549e611935c" xlink:to="loc_pwp_PaymentOfFinancingAndStockIssuanceCostsPricePerShare_6cee1bc8-5ab8-4cbd-abcc-13183f322881" xlink:type="arc" order="28"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentOfFinancingAndStockIssuanceCosts_80dd2e1b-aa0e-4ba8-a33d-31d156dde368" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PaymentOfFinancingAndStockIssuanceCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_f4c6b3a0-82c0-4a2e-b99a-e549e611935c" xlink:to="loc_us-gaap_PaymentOfFinancingAndStockIssuanceCosts_80dd2e1b-aa0e-4ba8-a33d-31d156dde368" xlink:type="arc" order="29"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCostsCurrent_9c0a6490-8efa-4a18-8733-736cd2285637" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DeferredCostsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_f4c6b3a0-82c0-4a2e-b99a-e549e611935c" xlink:to="loc_us-gaap_DeferredCostsCurrent_9c0a6490-8efa-4a18-8733-736cd2285637" xlink:type="arc" order="30"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_eb379c1a-fa69-4b68-82b4-700a65389bb3" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_f4c6b3a0-82c0-4a2e-b99a-e549e611935c" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_eb379c1a-fa69-4b68-82b4-700a65389bb3" xlink:type="arc" order="31"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfStockByClassTable_1fb599e4-637a-4b22-b434-992cc7961222" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfStockByClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfStockLineItems_f4c6b3a0-82c0-4a2e-b99a-e549e611935c" xlink:to="loc_us-gaap_ScheduleOfStockByClassTable_1fb599e4-637a-4b22-b434-992cc7961222" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_57d487a4-9d9e-418f-a0c0-fa19ccda638e" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_1fb599e4-637a-4b22-b434-992cc7961222" xlink:to="loc_us-gaap_StatementClassOfStockAxis_57d487a4-9d9e-418f-a0c0-fa19ccda638e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_57d487a4-9d9e-418f-a0c0-fa19ccda638e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_57d487a4-9d9e-418f-a0c0-fa19ccda638e" xlink:to="loc_us-gaap_ClassOfStockDomain_57d487a4-9d9e-418f-a0c0-fa19ccda638e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_b73deb90-a6a0-4890-82a0-dee7c72c540c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_57d487a4-9d9e-418f-a0c0-fa19ccda638e" xlink:to="loc_us-gaap_ClassOfStockDomain_b73deb90-a6a0-4890-82a0-dee7c72c540c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_4a8ba3dd-c474-4ac3-bd83-8fb27bb60086" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_b73deb90-a6a0-4890-82a0-dee7c72c540c" xlink:to="loc_us-gaap_CommonClassAMember_4a8ba3dd-c474-4ac3-bd83-8fb27bb60086" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_ClassB1CommonStockMember_adecb3a3-0b10-45f0-b8d4-fcac6bdf6e2d" xlink:href="pwp-20221231.xsd#pwp_ClassB1CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_b73deb90-a6a0-4890-82a0-dee7c72c540c" xlink:to="loc_pwp_ClassB1CommonStockMember_adecb3a3-0b10-45f0-b8d4-fcac6bdf6e2d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_ClassB2CommonStockMember_74229ec9-220c-45a4-b037-64cd06ca6333" xlink:href="pwp-20221231.xsd#pwp_ClassB2CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_b73deb90-a6a0-4890-82a0-dee7c72c540c" xlink:to="loc_pwp_ClassB2CommonStockMember_74229ec9-220c-45a4-b037-64cd06ca6333" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassBMember_fa9ad925-d762-40be-b3b1-4101771436f6" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonClassBMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_b73deb90-a6a0-4890-82a0-dee7c72c540c" xlink:to="loc_us-gaap_CommonClassBMember_fa9ad925-d762-40be-b3b1-4101771436f6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipAxis_d2d76f4f-62c7-407e-b817-01fc8cd424a3" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_OwnershipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_1fb599e4-637a-4b22-b434-992cc7961222" xlink:to="loc_srt_OwnershipAxis_d2d76f4f-62c7-407e-b817-01fc8cd424a3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_d2d76f4f-62c7-407e-b817-01fc8cd424a3_default" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_OwnershipAxis_d2d76f4f-62c7-407e-b817-01fc8cd424a3" xlink:to="loc_srt_OwnershipDomain_d2d76f4f-62c7-407e-b817-01fc8cd424a3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_2ee3d244-8fba-4ece-8bf5-a0edac624903" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_OwnershipAxis_d2d76f4f-62c7-407e-b817-01fc8cd424a3" xlink:to="loc_srt_OwnershipDomain_2ee3d244-8fba-4ece-8bf5-a0edac624903" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_ProfessionalPartnersAndIlpsMember_22e3fda4-c42b-4810-b522-fb5925223784" xlink:href="pwp-20221231.xsd#pwp_ProfessionalPartnersAndIlpsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_OwnershipDomain_2ee3d244-8fba-4ece-8bf5-a0edac624903" xlink:to="loc_pwp_ProfessionalPartnersAndIlpsMember_22e3fda4-c42b-4810-b522-fb5925223784" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_aa3d6f0f-a49b-4942-b84b-b8c6d9a45d06" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_1fb599e4-637a-4b22-b434-992cc7961222" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_aa3d6f0f-a49b-4942-b84b-b8c6d9a45d06" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_aa3d6f0f-a49b-4942-b84b-b8c6d9a45d06_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_aa3d6f0f-a49b-4942-b84b-b8c6d9a45d06" xlink:to="loc_us-gaap_RelatedPartyDomain_aa3d6f0f-a49b-4942-b84b-b8c6d9a45d06_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_1635d759-f0c9-4b72-913f-83c0ab97d7d7" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_aa3d6f0f-a49b-4942-b84b-b8c6d9a45d06" xlink:to="loc_us-gaap_RelatedPartyDomain_1635d759-f0c9-4b72-913f-83c0ab97d7d7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_FounderSharePurchaseOptionMember_6711882b-ffc9-49f6-9c04-e0ef82c6f035" xlink:href="pwp-20221231.xsd#pwp_FounderSharePurchaseOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_1635d759-f0c9-4b72-913f-83c0ab97d7d7" xlink:to="loc_pwp_FounderSharePurchaseOptionMember_6711882b-ffc9-49f6-9c04-e0ef82c6f035" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_WorkingPartnersMember_73bcc76f-0ddb-4c75-b9de-dfeb648ea9fd" xlink:href="pwp-20221231.xsd#pwp_WorkingPartnersMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_1635d759-f0c9-4b72-913f-83c0ab97d7d7" xlink:to="loc_pwp_WorkingPartnersMember_73bcc76f-0ddb-4c75-b9de-dfeb648ea9fd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_ExistingInvestorLimitedPartnersMember_4685854d-9206-4186-b572-83a46753c7e5" xlink:href="pwp-20221231.xsd#pwp_ExistingInvestorLimitedPartnersMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_1635d759-f0c9-4b72-913f-83c0ab97d7d7" xlink:to="loc_pwp_ExistingInvestorLimitedPartnersMember_4685854d-9206-4186-b572-83a46753c7e5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_OthersMember_ea41e38d-f017-414f-b5d8-984a250e4ca2" xlink:href="pwp-20221231.xsd#pwp_OthersMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_1635d759-f0c9-4b72-913f-83c0ab97d7d7" xlink:to="loc_pwp_OthersMember_ea41e38d-f017-414f-b5d8-984a250e4ca2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_FormerWorkingPartnersMember_14869db8-2c64-4ffd-8b70-e3f0f0512b6d" xlink:href="pwp-20221231.xsd#pwp_FormerWorkingPartnersMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_1635d759-f0c9-4b72-913f-83c0ab97d7d7" xlink:to="loc_pwp_FormerWorkingPartnersMember_14869db8-2c64-4ffd-8b70-e3f0f0512b6d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_68e8ea7b-456e-4727-a019-6df36b541ed4" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_1fb599e4-637a-4b22-b434-992cc7961222" xlink:to="loc_srt_RangeAxis_68e8ea7b-456e-4727-a019-6df36b541ed4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_68e8ea7b-456e-4727-a019-6df36b541ed4_default" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_68e8ea7b-456e-4727-a019-6df36b541ed4" xlink:to="loc_srt_RangeMember_68e8ea7b-456e-4727-a019-6df36b541ed4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_0bd37943-7bea-429a-b07b-76f177b4f3b9" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_68e8ea7b-456e-4727-a019-6df36b541ed4" xlink:to="loc_srt_RangeMember_0bd37943-7bea-429a-b07b-76f177b4f3b9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_ca953819-a9db-4984-a527-f9d093eacf35" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_0bd37943-7bea-429a-b07b-76f177b4f3b9" xlink:to="loc_srt_MinimumMember_ca953819-a9db-4984-a527-f9d093eacf35" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_16c86433-b7e1-4cab-a7ea-fe160e2c2e9f" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_0bd37943-7bea-429a-b07b-76f177b4f3b9" xlink:to="loc_srt_MaximumMember_16c86433-b7e1-4cab-a7ea-fe160e2c2e9f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis_2749e7c4-e11a-4a00-b273-780976680c5b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_1fb599e4-637a-4b22-b434-992cc7961222" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis_2749e7c4-e11a-4a00-b273-780976680c5b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2749e7c4-e11a-4a00-b273-780976680c5b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis_2749e7c4-e11a-4a00-b273-780976680c5b" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2749e7c4-e11a-4a00-b273-780976680c5b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_9e98a80a-53a8-4fcc-a993-0b5f64c70290" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis_2749e7c4-e11a-4a00-b273-780976680c5b" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_9e98a80a-53a8-4fcc-a993-0b5f64c70290" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_DollarTwelvePriceMember_455f42a7-ff5d-48bc-abdd-20c6d705a75c" xlink:href="pwp-20221231.xsd#pwp_DollarTwelvePriceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_9e98a80a-53a8-4fcc-a993-0b5f64c70290" xlink:to="loc_pwp_DollarTwelvePriceMember_455f42a7-ff5d-48bc-abdd-20c6d705a75c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_DollarFifteenPriceMember_442c60b7-5bbc-41cb-9467-51f31df21683" xlink:href="pwp-20221231.xsd#pwp_DollarFifteenPriceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_9e98a80a-53a8-4fcc-a993-0b5f64c70290" xlink:to="loc_pwp_DollarFifteenPriceMember_442c60b7-5bbc-41cb-9467-51f31df21683" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsidiarySaleOfStockAxis_491b5389-1485-4ef5-98f0-8300919710d1" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SubsidiarySaleOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_1fb599e4-637a-4b22-b434-992cc7961222" xlink:to="loc_us-gaap_SubsidiarySaleOfStockAxis_491b5389-1485-4ef5-98f0-8300919710d1" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_491b5389-1485-4ef5-98f0-8300919710d1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_491b5389-1485-4ef5-98f0-8300919710d1" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_491b5389-1485-4ef5-98f0-8300919710d1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_8b3efaf2-ccc8-4774-a094-2af9132d83bd" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_491b5389-1485-4ef5-98f0-8300919710d1" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_8b3efaf2-ccc8-4774-a094-2af9132d83bd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_FollowOnPublicOfferingMember_2e4cd830-a542-4418-94cd-2998474a8781" xlink:href="pwp-20221231.xsd#pwp_FollowOnPublicOfferingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_8b3efaf2-ccc8-4774-a094-2af9132d83bd" xlink:to="loc_pwp_FollowOnPublicOfferingMember_2e4cd830-a542-4418-94cd-2998474a8781" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_07cec7e5-173b-48d5-9f65-2db2f049e55a" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_1fb599e4-637a-4b22-b434-992cc7961222" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_07cec7e5-173b-48d5-9f65-2db2f049e55a" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_07cec7e5-173b-48d5-9f65-2db2f049e55a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_07cec7e5-173b-48d5-9f65-2db2f049e55a" xlink:to="loc_us-gaap_EquityComponentDomain_07cec7e5-173b-48d5-9f65-2db2f049e55a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_fe17592a-3592-4c51-bee4-7cb1f0b2d2aa" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_07cec7e5-173b-48d5-9f65-2db2f049e55a" xlink:to="loc_us-gaap_EquityComponentDomain_fe17592a-3592-4c51-bee4-7cb1f0b2d2aa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_90539e3e-431e-4b18-8c39-4f41ece55325" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_fe17592a-3592-4c51-bee4-7cb1f0b2d2aa" xlink:to="loc_us-gaap_CommonStockMember_90539e3e-431e-4b18-8c39-4f41ece55325" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pwp.com/role/WarrantsAdditionalInformationDetails" xlink:type="simple" xlink:href="pwp-20221231.xsd#WarrantsAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://pwp.com/role/WarrantsAdditionalInformationDetails" xlink:type="extended" id="if8a5129554104dd4a76ad1302cb9244a_WarrantsAdditionalInformationDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightLineItems_c55f6b73-d742-4dfe-8e4a-aba309486eb6" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfWarrantOrRightLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByEachWarrantOrRight_1d8b617f-e744-43c8-ad1b-60100358da05" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByEachWarrantOrRight"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems_c55f6b73-d742-4dfe-8e4a-aba309486eb6" xlink:to="loc_us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByEachWarrantOrRight_1d8b617f-e744-43c8-ad1b-60100358da05" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_ClassOfWarrantOrRightExercisedOrRedeemed_e312b363-f166-45ce-8cf4-94cf1374b345" xlink:href="pwp-20221231.xsd#pwp_ClassOfWarrantOrRightExercisedOrRedeemed"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems_c55f6b73-d742-4dfe-8e4a-aba309486eb6" xlink:to="loc_pwp_ClassOfWarrantOrRightExercisedOrRedeemed_e312b363-f166-45ce-8cf4-94cf1374b345" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights_e1ed942b-14f4-4d5d-87c6-54a372a308a3" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems_c55f6b73-d742-4dfe-8e4a-aba309486eb6" xlink:to="loc_us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights_e1ed942b-14f4-4d5d-87c6-54a372a308a3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_ClassOfWarrantOrRightExchangeCosts_51ed3c44-dba3-411d-88b0-cbc7a3c83bf8" xlink:href="pwp-20221231.xsd#pwp_ClassOfWarrantOrRightExchangeCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems_c55f6b73-d742-4dfe-8e4a-aba309486eb6" xlink:to="loc_pwp_ClassOfWarrantOrRightExchangeCosts_51ed3c44-dba3-411d-88b0-cbc7a3c83bf8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightOutstanding_6bcd82e5-0cb5-49c6-965b-d632ad975ec1" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfWarrantOrRightOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems_c55f6b73-d742-4dfe-8e4a-aba309486eb6" xlink:to="loc_us-gaap_ClassOfWarrantOrRightOutstanding_6bcd82e5-0cb5-49c6-965b-d632ad975ec1" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_499c0e4e-208b-46ad-87bf-cab44611a4c5" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems_c55f6b73-d742-4dfe-8e4a-aba309486eb6" xlink:to="loc_us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_499c0e4e-208b-46ad-87bf-cab44611a4c5" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightTable_f2e141a6-9c95-4a1e-bc5a-039d59a6d63f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfWarrantOrRightTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems_c55f6b73-d742-4dfe-8e4a-aba309486eb6" xlink:to="loc_us-gaap_ClassOfWarrantOrRightTable_f2e141a6-9c95-4a1e-bc5a-039d59a6d63f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightAxis_296acfde-77d1-4eb7-837a-d14ab275f77c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfWarrantOrRightAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ClassOfWarrantOrRightTable_f2e141a6-9c95-4a1e-bc5a-039d59a6d63f" xlink:to="loc_us-gaap_ClassOfWarrantOrRightAxis_296acfde-77d1-4eb7-837a-d14ab275f77c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightDomain_296acfde-77d1-4eb7-837a-d14ab275f77c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfWarrantOrRightDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ClassOfWarrantOrRightAxis_296acfde-77d1-4eb7-837a-d14ab275f77c" xlink:to="loc_us-gaap_ClassOfWarrantOrRightDomain_296acfde-77d1-4eb7-837a-d14ab275f77c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightDomain_3e8985b1-6d9c-4a4e-8307-7a6b1dfaef27" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfWarrantOrRightDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ClassOfWarrantOrRightAxis_296acfde-77d1-4eb7-837a-d14ab275f77c" xlink:to="loc_us-gaap_ClassOfWarrantOrRightDomain_3e8985b1-6d9c-4a4e-8307-7a6b1dfaef27" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_PublicWarrantsMember_74a166ed-4da7-4665-a800-d73078e16d92" xlink:href="pwp-20221231.xsd#pwp_PublicWarrantsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightDomain_3e8985b1-6d9c-4a4e-8307-7a6b1dfaef27" xlink:to="loc_pwp_PublicWarrantsMember_74a166ed-4da7-4665-a800-d73078e16d92" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_PrivatePlacementWarrantsMember_03b73a83-cf14-4ff4-8420-a84177acc53b" xlink:href="pwp-20221231.xsd#pwp_PrivatePlacementWarrantsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightDomain_3e8985b1-6d9c-4a4e-8307-7a6b1dfaef27" xlink:to="loc_pwp_PrivatePlacementWarrantsMember_03b73a83-cf14-4ff4-8420-a84177acc53b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_ValidTenderMember_6634abb1-084c-4c60-a866-684095be41c9" xlink:href="pwp-20221231.xsd#pwp_ValidTenderMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightDomain_3e8985b1-6d9c-4a4e-8307-7a6b1dfaef27" xlink:to="loc_pwp_ValidTenderMember_6634abb1-084c-4c60-a866-684095be41c9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_ForcedTenderMember_c138b3c6-dd68-4a5d-80f3-6b0684c86d26" xlink:href="pwp-20221231.xsd#pwp_ForcedTenderMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightDomain_3e8985b1-6d9c-4a4e-8307-7a6b1dfaef27" xlink:to="loc_pwp_ForcedTenderMember_c138b3c6-dd68-4a5d-80f3-6b0684c86d26" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_724baea9-9d8c-4cd0-b708-4ba9076c3706" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ClassOfWarrantOrRightTable_f2e141a6-9c95-4a1e-bc5a-039d59a6d63f" xlink:to="loc_us-gaap_StatementClassOfStockAxis_724baea9-9d8c-4cd0-b708-4ba9076c3706" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_724baea9-9d8c-4cd0-b708-4ba9076c3706_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_724baea9-9d8c-4cd0-b708-4ba9076c3706" xlink:to="loc_us-gaap_ClassOfStockDomain_724baea9-9d8c-4cd0-b708-4ba9076c3706_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_20f27b12-4763-42d8-8266-efe63a7a90c5" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_724baea9-9d8c-4cd0-b708-4ba9076c3706" xlink:to="loc_us-gaap_ClassOfStockDomain_20f27b12-4763-42d8-8266-efe63a7a90c5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_a212ed48-b3ec-48f5-8574-a7ae18676276" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_20f27b12-4763-42d8-8266-efe63a7a90c5" xlink:to="loc_us-gaap_CommonClassAMember_a212ed48-b3ec-48f5-8574-a7ae18676276" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pwp.com/role/EquityBasedCompensationAdditionalInformationDetails" xlink:type="simple" xlink:href="pwp-20221231.xsd#EquityBasedCompensationAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://pwp.com/role/EquityBasedCompensationAdditionalInformationDetails" xlink:type="extended" id="if8ba5f1998db400ebc3c8f4e43aa2830_EquityBasedCompensationAdditionalInformationDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_fb1b2b41-01a8-479c-b372-ebe0e24c9f8d" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_PercentageOfSharesOutstanding_b9b9f581-5d93-435d-bfc8-77ce1ed01f79" xlink:href="pwp-20221231.xsd#pwp_PercentageOfSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_fb1b2b41-01a8-479c-b372-ebe0e24c9f8d" xlink:to="loc_pwp_PercentageOfSharesOutstanding_b9b9f581-5d93-435d-bfc8-77ce1ed01f79" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_cfc9dcdc-e73d-4d66-b9c0-4bf631c70aaa" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_fb1b2b41-01a8-479c-b372-ebe0e24c9f8d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_cfc9dcdc-e73d-4d66-b9c0-4bf631c70aaa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_ed86b835-2a71-4b0d-9fbc-7318e2a586d0" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_fb1b2b41-01a8-479c-b372-ebe0e24c9f8d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_ed86b835-2a71-4b0d-9fbc-7318e2a586d0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_6216f2e0-43c0-414a-9f75-51a723a71cb2" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_fb1b2b41-01a8-479c-b372-ebe0e24c9f8d" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_6216f2e0-43c0-414a-9f75-51a723a71cb2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_MarketConditionSharePriceRequirement_dceabf5a-39f2-4006-aeb4-b69481c4d843" xlink:href="pwp-20221231.xsd#pwp_MarketConditionSharePriceRequirement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_fb1b2b41-01a8-479c-b372-ebe0e24c9f8d" xlink:to="loc_pwp_MarketConditionSharePriceRequirement_dceabf5a-39f2-4006-aeb4-b69481c4d843" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_PeriodRequiredToAchieveCertainConditions_0aa955a2-4ccb-425f-ae48-560a002caf03" xlink:href="pwp-20221231.xsd#pwp_PeriodRequiredToAchieveCertainConditions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_fb1b2b41-01a8-479c-b372-ebe0e24c9f8d" xlink:to="loc_pwp_PeriodRequiredToAchieveCertainConditions_0aa955a2-4ccb-425f-ae48-560a002caf03" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_ThresholdPeriodRequiredForSatisfyCertainConditions_467c4231-c9a9-4b8e-98ea-f8ea77822154" xlink:href="pwp-20221231.xsd#pwp_ThresholdPeriodRequiredForSatisfyCertainConditions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_fb1b2b41-01a8-479c-b372-ebe0e24c9f8d" xlink:to="loc_pwp_ThresholdPeriodRequiredForSatisfyCertainConditions_467c4231-c9a9-4b8e-98ea-f8ea77822154" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_MarketConditionSharePriceAchieved_9a1bf483-392b-448a-b15b-50ee8899dbc5" xlink:href="pwp-20221231.xsd#pwp_MarketConditionSharePriceAchieved"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_fb1b2b41-01a8-479c-b372-ebe0e24c9f8d" xlink:to="loc_pwp_MarketConditionSharePriceAchieved_9a1bf483-392b-448a-b15b-50ee8899dbc5" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_3f317a1f-2297-4552-87d8-63bcf8d29faf" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_fb1b2b41-01a8-479c-b372-ebe0e24c9f8d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_3f317a1f-2297-4552-87d8-63bcf8d29faf" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue_71bb18a6-a90e-4f88-86c8-ef56cb5d9c33" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_fb1b2b41-01a8-479c-b372-ebe0e24c9f8d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue_71bb18a6-a90e-4f88-86c8-ef56cb5d9c33" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_dbaaf7b3-6f1d-4c4c-8fa9-c3e9464b8b12" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_fb1b2b41-01a8-479c-b372-ebe0e24c9f8d" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_dbaaf7b3-6f1d-4c4c-8fa9-c3e9464b8b12" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_fe897b94-a3a0-4282-83aa-1f18c104f279" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_fb1b2b41-01a8-479c-b372-ebe0e24c9f8d" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_fe897b94-a3a0-4282-83aa-1f18c104f279" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodGrantDateFairValue_6b8e360d-db76-4cdf-a1c2-d8b896b22e8e" xlink:href="pwp-20221231.xsd#pwp_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_fb1b2b41-01a8-479c-b372-ebe0e24c9f8d" xlink:to="loc_pwp_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodGrantDateFairValue_6b8e360d-db76-4cdf-a1c2-d8b896b22e8e" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_ShareBasedCompensationArrangementByShareBasedPaymentAwardPlanModificationGrantDateFairValue_d84c8156-e689-4d7b-8d5b-a65717622922" xlink:href="pwp-20221231.xsd#pwp_ShareBasedCompensationArrangementByShareBasedPaymentAwardPlanModificationGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_fb1b2b41-01a8-479c-b372-ebe0e24c9f8d" xlink:to="loc_pwp_ShareBasedCompensationArrangementByShareBasedPaymentAwardPlanModificationGrantDateFairValue_d84c8156-e689-4d7b-8d5b-a65717622922" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsMeasurementInput_3801e548-4eca-4c96-bcac-5bba002bd7f0" xlink:href="pwp-20221231.xsd#pwp_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsMeasurementInput"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_fb1b2b41-01a8-479c-b372-ebe0e24c9f8d" xlink:to="loc_pwp_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsMeasurementInput_3801e548-4eca-4c96-bcac-5bba002bd7f0" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_3d776f63-e422-4053-9382-3dc3b1012459" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_fb1b2b41-01a8-479c-b372-ebe0e24c9f8d" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_3d776f63-e422-4053-9382-3dc3b1012459" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_c595cac3-4df7-446d-89bb-f7b7b8907a5e" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_3d776f63-e422-4053-9382-3dc3b1012459" xlink:to="loc_srt_RangeAxis_c595cac3-4df7-446d-89bb-f7b7b8907a5e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_c595cac3-4df7-446d-89bb-f7b7b8907a5e_default" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_c595cac3-4df7-446d-89bb-f7b7b8907a5e" xlink:to="loc_srt_RangeMember_c595cac3-4df7-446d-89bb-f7b7b8907a5e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_66a4bf01-efe5-4ade-81af-4970739d0bd8" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_c595cac3-4df7-446d-89bb-f7b7b8907a5e" xlink:to="loc_srt_RangeMember_66a4bf01-efe5-4ade-81af-4970739d0bd8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_a1710b0a-a101-4634-9f2e-6183726972f9" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_66a4bf01-efe5-4ade-81af-4970739d0bd8" xlink:to="loc_srt_MinimumMember_a1710b0a-a101-4634-9f2e-6183726972f9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_b151bc90-19c9-4a2e-a9e7-3cc9c295ca87" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_66a4bf01-efe5-4ade-81af-4970739d0bd8" xlink:to="loc_srt_MaximumMember_b151bc90-19c9-4a2e-a9e7-3cc9c295ca87" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_29939cdb-190d-467e-b369-2fe922a3952c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_3d776f63-e422-4053-9382-3dc3b1012459" xlink:to="loc_us-gaap_AwardTypeAxis_29939cdb-190d-467e-b369-2fe922a3952c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_29939cdb-190d-467e-b369-2fe922a3952c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_29939cdb-190d-467e-b369-2fe922a3952c" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_29939cdb-190d-467e-b369-2fe922a3952c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_eba7735c-3788-49e3-ae42-50838cb1e581" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_29939cdb-190d-467e-b369-2fe922a3952c" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_eba7735c-3788-49e3-ae42-50838cb1e581" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_TransactionPoolPsusMember_31df7a98-5919-4d42-9b1c-cc7a1ecf3559" xlink:href="pwp-20221231.xsd#pwp_TransactionPoolPsusMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_eba7735c-3788-49e3-ae42-50838cb1e581" xlink:to="loc_pwp_TransactionPoolPsusMember_31df7a98-5919-4d42-9b1c-cc7a1ecf3559" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_TransactionPoolRsusMember_233a4314-934d-427d-ace3-5b283a713e36" xlink:href="pwp-20221231.xsd#pwp_TransactionPoolRsusMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_eba7735c-3788-49e3-ae42-50838cb1e581" xlink:to="loc_pwp_TransactionPoolRsusMember_233a4314-934d-427d-ace3-5b283a713e36" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_LongTermIncentiveAwardsMember_adf48788-59b2-4db2-b28f-3ef2cc566f44" xlink:href="pwp-20221231.xsd#pwp_LongTermIncentiveAwardsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_eba7735c-3788-49e3-ae42-50838cb1e581" xlink:to="loc_pwp_LongTermIncentiveAwardsMember_adf48788-59b2-4db2-b28f-3ef2cc566f44" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_GeneralRsusMember_1b4d1877-0874-40ee-8a32-f6d772f35e9f" xlink:href="pwp-20221231.xsd#pwp_GeneralRsusMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_eba7735c-3788-49e3-ae42-50838cb1e581" xlink:to="loc_pwp_GeneralRsusMember_1b4d1877-0874-40ee-8a32-f6d772f35e9f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_ProfessionalPartnersAwardMember_5ebb376f-8eb8-45c8-bb18-69d289617e30" xlink:href="pwp-20221231.xsd#pwp_ProfessionalPartnersAwardMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_eba7735c-3788-49e3-ae42-50838cb1e581" xlink:to="loc_pwp_ProfessionalPartnersAwardMember_5ebb376f-8eb8-45c8-bb18-69d289617e30" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_LegacyAwardsMember_924d4b21-9d87-4848-a62e-24e4b792241e" xlink:href="pwp-20221231.xsd#pwp_LegacyAwardsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_eba7735c-3788-49e3-ae42-50838cb1e581" xlink:to="loc_pwp_LegacyAwardsMember_924d4b21-9d87-4848-a62e-24e4b792241e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_7c45c49b-18e0-4e7c-9662-674c68c8c40b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_3d776f63-e422-4053-9382-3dc3b1012459" xlink:to="loc_us-gaap_PlanNameAxis_7c45c49b-18e0-4e7c-9662-674c68c8c40b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_7c45c49b-18e0-4e7c-9662-674c68c8c40b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_7c45c49b-18e0-4e7c-9662-674c68c8c40b" xlink:to="loc_us-gaap_PlanNameDomain_7c45c49b-18e0-4e7c-9662-674c68c8c40b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_0860135d-c893-43b8-8ef3-da4358417ab9" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_7c45c49b-18e0-4e7c-9662-674c68c8c40b" xlink:to="loc_us-gaap_PlanNameDomain_0860135d-c893-43b8-8ef3-da4358417ab9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_PerellaWeinbergPartners2021OmnibusIncentivePlanMember_c11d31da-5e5d-4f1d-9d86-2a55b53c5c2d" xlink:href="pwp-20221231.xsd#pwp_PerellaWeinbergPartners2021OmnibusIncentivePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_0860135d-c893-43b8-8ef3-da4358417ab9" xlink:to="loc_pwp_PerellaWeinbergPartners2021OmnibusIncentivePlanMember_c11d31da-5e5d-4f1d-9d86-2a55b53c5c2d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingAxis_1ddc69d5-8849-415f-94d3-c464c428f9e9" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_VestingAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_3d776f63-e422-4053-9382-3dc3b1012459" xlink:to="loc_us-gaap_VestingAxis_1ddc69d5-8849-415f-94d3-c464c428f9e9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingDomain_1ddc69d5-8849-415f-94d3-c464c428f9e9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_VestingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VestingAxis_1ddc69d5-8849-415f-94d3-c464c428f9e9" xlink:to="loc_us-gaap_VestingDomain_1ddc69d5-8849-415f-94d3-c464c428f9e9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingDomain_ca81df72-7ca9-497a-8919-c008abebeb68" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_VestingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VestingAxis_1ddc69d5-8849-415f-94d3-c464c428f9e9" xlink:to="loc_us-gaap_VestingDomain_ca81df72-7ca9-497a-8919-c008abebeb68" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_OneTwoPriceTrancheMember_4c8ac2e1-63fa-416c-a3e7-330d8181cd3a" xlink:href="pwp-20221231.xsd#pwp_OneTwoPriceTrancheMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_ca81df72-7ca9-497a-8919-c008abebeb68" xlink:to="loc_pwp_OneTwoPriceTrancheMember_4c8ac2e1-63fa-416c-a3e7-330d8181cd3a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_OneThreePointFiveZeroPriceTrancheMember_e2cbf370-f7c6-46b1-9a10-edc516a2f30d" xlink:href="pwp-20221231.xsd#pwp_OneThreePointFiveZeroPriceTrancheMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_ca81df72-7ca9-497a-8919-c008abebeb68" xlink:to="loc_pwp_OneThreePointFiveZeroPriceTrancheMember_e2cbf370-f7c6-46b1-9a10-edc516a2f30d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_OneFivePriceTrancheMember_5cd7d04e-5ae2-4e42-8139-09146edd0fc0" xlink:href="pwp-20221231.xsd#pwp_OneFivePriceTrancheMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_ca81df72-7ca9-497a-8919-c008abebeb68" xlink:to="loc_pwp_OneFivePriceTrancheMember_5cd7d04e-5ae2-4e42-8139-09146edd0fc0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_OneSevenPriceTrancheMember_f9b65c7b-4eb3-485c-89b4-719c3a2838b7" xlink:href="pwp-20221231.xsd#pwp_OneSevenPriceTrancheMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_ca81df72-7ca9-497a-8919-c008abebeb68" xlink:to="loc_pwp_OneSevenPriceTrancheMember_f9b65c7b-4eb3-485c-89b4-719c3a2838b7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_ThirtySixMonthsTrancheMember_5b3ca8fc-f811-4d83-8135-960af3e79475" xlink:href="pwp-20221231.xsd#pwp_ThirtySixMonthsTrancheMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_ca81df72-7ca9-497a-8919-c008abebeb68" xlink:to="loc_pwp_ThirtySixMonthsTrancheMember_5b3ca8fc-f811-4d83-8135-960af3e79475" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_FourtyTwoMonthsTrancheMember_bc36cf4b-adcb-440d-bde3-75bf59395609" xlink:href="pwp-20221231.xsd#pwp_FourtyTwoMonthsTrancheMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_ca81df72-7ca9-497a-8919-c008abebeb68" xlink:to="loc_pwp_FourtyTwoMonthsTrancheMember_bc36cf4b-adcb-440d-bde3-75bf59395609" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_FourtyEightMonthsTrancheMember_c73600f9-e23a-4378-9373-78e56fbfb823" xlink:href="pwp-20221231.xsd#pwp_FourtyEightMonthsTrancheMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_ca81df72-7ca9-497a-8919-c008abebeb68" xlink:to="loc_pwp_FourtyEightMonthsTrancheMember_c73600f9-e23a-4378-9373-78e56fbfb823" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_FiftyFourMonthsTrancheMember_0791064f-7bf3-460e-85e6-c31fa4b1d992" xlink:href="pwp-20221231.xsd#pwp_FiftyFourMonthsTrancheMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_ca81df72-7ca9-497a-8919-c008abebeb68" xlink:to="loc_pwp_FiftyFourMonthsTrancheMember_0791064f-7bf3-460e-85e6-c31fa4b1d992" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_SixtyMonthsTrancheMember_9e83269d-e57b-4338-b59d-e802747539df" xlink:href="pwp-20221231.xsd#pwp_SixtyMonthsTrancheMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_ca81df72-7ca9-497a-8919-c008abebeb68" xlink:to="loc_pwp_SixtyMonthsTrancheMember_9e83269d-e57b-4338-b59d-e802747539df" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_TrancheOneMember_ab5e55b8-fdd1-47f6-a773-4e2c4b028649" xlink:href="pwp-20221231.xsd#pwp_TrancheOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_ca81df72-7ca9-497a-8919-c008abebeb68" xlink:to="loc_pwp_TrancheOneMember_ab5e55b8-fdd1-47f6-a773-4e2c4b028649" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_TrancheTwoMember_df1900d8-384b-41b0-ba6f-13166e0639a1" xlink:href="pwp-20221231.xsd#pwp_TrancheTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_ca81df72-7ca9-497a-8919-c008abebeb68" xlink:to="loc_pwp_TrancheTwoMember_df1900d8-384b-41b0-ba6f-13166e0639a1" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_TrancheThreeMember_174d7cd4-941c-4c7d-9e0e-11e4c63741f1" xlink:href="pwp-20221231.xsd#pwp_TrancheThreeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_ca81df72-7ca9-497a-8919-c008abebeb68" xlink:to="loc_pwp_TrancheThreeMember_174d7cd4-941c-4c7d-9e0e-11e4c63741f1" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_TrancheFourMember_f2c10960-fd28-4afc-b4a4-163380f83919" xlink:href="pwp-20221231.xsd#pwp_TrancheFourMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_ca81df72-7ca9-497a-8919-c008abebeb68" xlink:to="loc_pwp_TrancheFourMember_f2c10960-fd28-4afc-b4a4-163380f83919" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeAxis_de47813e-5fc5-431e-b873-92d95a02736c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_MeasurementInputTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_3d776f63-e422-4053-9382-3dc3b1012459" xlink:to="loc_us-gaap_MeasurementInputTypeAxis_de47813e-5fc5-431e-b873-92d95a02736c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_de47813e-5fc5-431e-b873-92d95a02736c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_de47813e-5fc5-431e-b873-92d95a02736c" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_de47813e-5fc5-431e-b873-92d95a02736c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_6a340173-d50a-4ae8-b6d1-e0ae8860a991" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_de47813e-5fc5-431e-b873-92d95a02736c" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_6a340173-d50a-4ae8-b6d1-e0ae8860a991" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputDiscountRateMember_ec318ae6-7e1c-4e62-9c34-4587aebd4614" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_MeasurementInputDiscountRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_6a340173-d50a-4ae8-b6d1-e0ae8860a991" xlink:to="loc_us-gaap_MeasurementInputDiscountRateMember_ec318ae6-7e1c-4e62-9c34-4587aebd4614" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueAxis_1e93076d-e95c-4e21-b86d-9eb4d6a3c972" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ValuationTechniqueAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_3d776f63-e422-4053-9382-3dc3b1012459" xlink:to="loc_us-gaap_ValuationTechniqueAxis_1e93076d-e95c-4e21-b86d-9eb4d6a3c972" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueDomain_1e93076d-e95c-4e21-b86d-9eb4d6a3c972_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ValuationTechniqueDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ValuationTechniqueAxis_1e93076d-e95c-4e21-b86d-9eb4d6a3c972" xlink:to="loc_us-gaap_ValuationTechniqueDomain_1e93076d-e95c-4e21-b86d-9eb4d6a3c972_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueDomain_32c0a32f-a359-4d44-a743-269814454f63" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ValuationTechniqueDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ValuationTechniqueAxis_1e93076d-e95c-4e21-b86d-9eb4d6a3c972" xlink:to="loc_us-gaap_ValuationTechniqueDomain_32c0a32f-a359-4d44-a743-269814454f63" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeApproachValuationTechniqueMember_ed99db11-f240-4113-b4c5-1002d83d3e32" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncomeApproachValuationTechniqueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ValuationTechniqueDomain_32c0a32f-a359-4d44-a743-269814454f63" xlink:to="loc_us-gaap_IncomeApproachValuationTechniqueMember_ed99db11-f240-4113-b4c5-1002d83d3e32" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pwp.com/role/EquityBasedCompensationSummaryofActivityRelatedtoUnvestedTransactionPoolPSUsDetails" xlink:type="simple" xlink:href="pwp-20221231.xsd#EquityBasedCompensationSummaryofActivityRelatedtoUnvestedTransactionPoolPSUsDetails"/>
  <link:definitionLink xlink:role="http://pwp.com/role/EquityBasedCompensationSummaryofActivityRelatedtoUnvestedTransactionPoolPSUsDetails" xlink:type="extended" id="i7b1172c5677c49fd90107677d9296386_EquityBasedCompensationSummaryofActivityRelatedtoUnvestedTransactionPoolPSUsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_b72db561-eb5f-4ed5-818a-503258221b62" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_f9bb8772-ea0b-4121-b2a7-47a18537d0c7" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_b72db561-eb5f-4ed5-818a-503258221b62" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_f9bb8772-ea0b-4121-b2a7-47a18537d0c7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_6cc29f1c-4176-44e9-b17f-9e10ca186589" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_f9bb8772-ea0b-4121-b2a7-47a18537d0c7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_6cc29f1c-4176-44e9-b17f-9e10ca186589" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_57924f96-e112-434e-8441-5ca16be07e80" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_f9bb8772-ea0b-4121-b2a7-47a18537d0c7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_57924f96-e112-434e-8441-5ca16be07e80" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_3286784a-b31a-4176-b1bd-89d6617e81ee" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_f9bb8772-ea0b-4121-b2a7-47a18537d0c7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_3286784a-b31a-4176-b1bd-89d6617e81ee" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_c7406b14-398a-4097-a7d7-2da93f72b6b2" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_f9bb8772-ea0b-4121-b2a7-47a18537d0c7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_c7406b14-398a-4097-a7d7-2da93f72b6b2" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_1fd93fd0-17ee-4940-8608-05454b1a14c1" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_c0ef8ee3-1690-479b-b119-0cb140faa835" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_b72db561-eb5f-4ed5-818a-503258221b62" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_c0ef8ee3-1690-479b-b119-0cb140faa835" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_c43e986c-59f6-4979-9679-7b32a4c78844" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_c0ef8ee3-1690-479b-b119-0cb140faa835" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_c43e986c-59f6-4979-9679-7b32a4c78844" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_7e709438-fc16-4102-a0d3-7113e1bf4269" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_c0ef8ee3-1690-479b-b119-0cb140faa835" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_7e709438-fc16-4102-a0d3-7113e1bf4269" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_f402280a-329f-4b4f-9e94-e25ee2200ab2" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_c0ef8ee3-1690-479b-b119-0cb140faa835" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_f402280a-329f-4b4f-9e94-e25ee2200ab2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_f7cac1da-99a1-4a62-850e-e6d3a4be56d4" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_c0ef8ee3-1690-479b-b119-0cb140faa835" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_f7cac1da-99a1-4a62-850e-e6d3a4be56d4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_38899e32-926f-4809-b976-99acabda795f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_b3abff16-2d4a-4a17-be32-868abad02727" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_b72db561-eb5f-4ed5-818a-503258221b62" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_b3abff16-2d4a-4a17-be32-868abad02727" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_82a671eb-bad3-46f5-ba11-1272bea37313" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_b3abff16-2d4a-4a17-be32-868abad02727" xlink:to="loc_us-gaap_AwardTypeAxis_82a671eb-bad3-46f5-ba11-1272bea37313" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_82a671eb-bad3-46f5-ba11-1272bea37313_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_82a671eb-bad3-46f5-ba11-1272bea37313" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_82a671eb-bad3-46f5-ba11-1272bea37313_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_644be243-f925-46d4-b1f3-629e681bca9e" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_82a671eb-bad3-46f5-ba11-1272bea37313" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_644be243-f925-46d4-b1f3-629e681bca9e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_TransactionPoolPsusMember_83ba192d-844b-4d27-a3ee-dfbac955eb5f" xlink:href="pwp-20221231.xsd#pwp_TransactionPoolPsusMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_644be243-f925-46d4-b1f3-629e681bca9e" xlink:to="loc_pwp_TransactionPoolPsusMember_83ba192d-844b-4d27-a3ee-dfbac955eb5f" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pwp.com/role/EquityBasedCompensationAssumptionsUsedinApplyingPricingModelDetails" xlink:type="simple" xlink:href="pwp-20221231.xsd#EquityBasedCompensationAssumptionsUsedinApplyingPricingModelDetails"/>
  <link:definitionLink xlink:role="http://pwp.com/role/EquityBasedCompensationAssumptionsUsedinApplyingPricingModelDetails" xlink:type="extended" id="i573d276969b34bfca92e8e8a74cefbb2_EquityBasedCompensationAssumptionsUsedinApplyingPricingModelDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_b7dc3fd2-aa83-4ab6-9e5a-72006fed1fac" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_c6a63fff-13e7-49c3-a0f3-f8c510ded024" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_b7dc3fd2-aa83-4ab6-9e5a-72006fed1fac" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_c6a63fff-13e7-49c3-a0f3-f8c510ded024" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_9bc76ce3-34cb-4204-8673-051fb999fa5f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_b7dc3fd2-aa83-4ab6-9e5a-72006fed1fac" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_9bc76ce3-34cb-4204-8673-051fb999fa5f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_3f250f13-8b3b-4557-867a-1d8fd19bd1bb" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_b7dc3fd2-aa83-4ab6-9e5a-72006fed1fac" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_3f250f13-8b3b-4557-867a-1d8fd19bd1bb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_4775832b-e14e-436a-bb68-0c3e4c179eb0" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_b7dc3fd2-aa83-4ab6-9e5a-72006fed1fac" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_4775832b-e14e-436a-bb68-0c3e4c179eb0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_80fafaf5-7028-47c0-8427-a32bdec5b8c8" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_4775832b-e14e-436a-bb68-0c3e4c179eb0" xlink:to="loc_us-gaap_AwardTypeAxis_80fafaf5-7028-47c0-8427-a32bdec5b8c8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_80fafaf5-7028-47c0-8427-a32bdec5b8c8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_80fafaf5-7028-47c0-8427-a32bdec5b8c8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_80fafaf5-7028-47c0-8427-a32bdec5b8c8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_28f31d46-8684-4a7b-8095-9644d8f69a8e" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_80fafaf5-7028-47c0-8427-a32bdec5b8c8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_28f31d46-8684-4a7b-8095-9644d8f69a8e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_TransactionPoolPsusMember_f72d547b-aedc-4002-ae73-995b3e00efa1" xlink:href="pwp-20221231.xsd#pwp_TransactionPoolPsusMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_28f31d46-8684-4a7b-8095-9644d8f69a8e" xlink:to="loc_pwp_TransactionPoolPsusMember_f72d547b-aedc-4002-ae73-995b3e00efa1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_LongTermIncentiveAwardsMember_185a9bb1-a226-452e-9aaf-f2489a4bf475" xlink:href="pwp-20221231.xsd#pwp_LongTermIncentiveAwardsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_28f31d46-8684-4a7b-8095-9644d8f69a8e" xlink:to="loc_pwp_LongTermIncentiveAwardsMember_185a9bb1-a226-452e-9aaf-f2489a4bf475" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pwp.com/role/EquityBasedCompensationSummaryofTransactionPoolRestrictedStockUnitsDetails" xlink:type="simple" xlink:href="pwp-20221231.xsd#EquityBasedCompensationSummaryofTransactionPoolRestrictedStockUnitsDetails"/>
  <link:definitionLink xlink:role="http://pwp.com/role/EquityBasedCompensationSummaryofTransactionPoolRestrictedStockUnitsDetails" xlink:type="extended" id="ia931778f88d341cd91451a04703a140a_EquityBasedCompensationSummaryofTransactionPoolRestrictedStockUnitsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1c447327-722c-48f9-8a41-2b401aa70af6" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_5cdca16e-c58f-4575-8c13-9c78d4ed36c9" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1c447327-722c-48f9-8a41-2b401aa70af6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_5cdca16e-c58f-4575-8c13-9c78d4ed36c9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_03d7e4c0-8cef-494b-9917-8a913f6d771d" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_5cdca16e-c58f-4575-8c13-9c78d4ed36c9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_03d7e4c0-8cef-494b-9917-8a913f6d771d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_6ae406c3-01ff-4849-8219-21e8c9251b9f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_5cdca16e-c58f-4575-8c13-9c78d4ed36c9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_6ae406c3-01ff-4849-8219-21e8c9251b9f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_b5afb930-38ad-4fa0-a0c1-aa134233521f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_5cdca16e-c58f-4575-8c13-9c78d4ed36c9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_b5afb930-38ad-4fa0-a0c1-aa134233521f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_edb6c5fb-fc69-4caf-a4bc-bcfb3156c7c4" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_5cdca16e-c58f-4575-8c13-9c78d4ed36c9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_edb6c5fb-fc69-4caf-a4bc-bcfb3156c7c4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_c71c029e-faa1-4a18-8c65-895c50983074" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_0fb339c7-6b38-4d65-a3a8-6e8145e612c3" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1c447327-722c-48f9-8a41-2b401aa70af6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_0fb339c7-6b38-4d65-a3a8-6e8145e612c3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_50026a65-d6a3-4945-a6b9-d48a5897e85a" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_0fb339c7-6b38-4d65-a3a8-6e8145e612c3" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_50026a65-d6a3-4945-a6b9-d48a5897e85a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_76bcff7b-e6d5-4e0c-a751-a088a1c10dd9" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_0fb339c7-6b38-4d65-a3a8-6e8145e612c3" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_76bcff7b-e6d5-4e0c-a751-a088a1c10dd9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_82609285-98d9-4732-90bb-cd9dc02a1473" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_0fb339c7-6b38-4d65-a3a8-6e8145e612c3" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_82609285-98d9-4732-90bb-cd9dc02a1473" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_003c987d-2675-4338-b2fb-548c56b7b43e" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_0fb339c7-6b38-4d65-a3a8-6e8145e612c3" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_003c987d-2675-4338-b2fb-548c56b7b43e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_7b476c6e-5362-4208-ac56-8dfeb010ac9c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_23f01fe3-7e4c-4564-9afd-0f8bce85ca87" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1c447327-722c-48f9-8a41-2b401aa70af6" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_23f01fe3-7e4c-4564-9afd-0f8bce85ca87" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_c05b8009-422b-4a05-ab9b-9db4316230ad" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_23f01fe3-7e4c-4564-9afd-0f8bce85ca87" xlink:to="loc_us-gaap_AwardTypeAxis_c05b8009-422b-4a05-ab9b-9db4316230ad" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_c05b8009-422b-4a05-ab9b-9db4316230ad_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_c05b8009-422b-4a05-ab9b-9db4316230ad" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_c05b8009-422b-4a05-ab9b-9db4316230ad_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_884c79a6-8bc3-4252-aa06-c6c59db6dd1e" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_c05b8009-422b-4a05-ab9b-9db4316230ad" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_884c79a6-8bc3-4252-aa06-c6c59db6dd1e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_TransactionPoolRsusMember_d8cdbee7-98cd-42a8-ba42-fb0eede02cfa" xlink:href="pwp-20221231.xsd#pwp_TransactionPoolRsusMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_884c79a6-8bc3-4252-aa06-c6c59db6dd1e" xlink:to="loc_pwp_TransactionPoolRsusMember_d8cdbee7-98cd-42a8-ba42-fb0eede02cfa" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pwp.com/role/EquityBasedCompensationSummaryofActivityRelatedtoUnvestedManagementPSUsDetails" xlink:type="simple" xlink:href="pwp-20221231.xsd#EquityBasedCompensationSummaryofActivityRelatedtoUnvestedManagementPSUsDetails"/>
  <link:definitionLink xlink:role="http://pwp.com/role/EquityBasedCompensationSummaryofActivityRelatedtoUnvestedManagementPSUsDetails" xlink:type="extended" id="ia9468fdb417846cd943acc660f5c05fc_EquityBasedCompensationSummaryofActivityRelatedtoUnvestedManagementPSUsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8408436a-06bd-4016-b18a-42f0b0e80fa9" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_015a5c6f-55b0-4642-9665-a49946adb88b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8408436a-06bd-4016-b18a-42f0b0e80fa9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_015a5c6f-55b0-4642-9665-a49946adb88b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_b83b3039-c469-426b-9f35-20a67190dcb9" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_015a5c6f-55b0-4642-9665-a49946adb88b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_b83b3039-c469-426b-9f35-20a67190dcb9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_b6775797-3549-46fd-b4f0-f54945b536a9" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_015a5c6f-55b0-4642-9665-a49946adb88b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_b6775797-3549-46fd-b4f0-f54945b536a9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_f5ca9d86-a32e-4536-80ba-d088edc86fb7" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_015a5c6f-55b0-4642-9665-a49946adb88b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_f5ca9d86-a32e-4536-80ba-d088edc86fb7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_22c38297-29a1-40a2-a6b5-4ebd3a6ca083" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_015a5c6f-55b0-4642-9665-a49946adb88b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_22c38297-29a1-40a2-a6b5-4ebd3a6ca083" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_829025b3-7030-4f68-ab16-2a716d397eb7" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_0d68c785-1c66-4b01-90b1-e811fc3e0a17" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8408436a-06bd-4016-b18a-42f0b0e80fa9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_0d68c785-1c66-4b01-90b1-e811fc3e0a17" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_8f364657-91fa-410f-9453-fff9d834c096" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_0d68c785-1c66-4b01-90b1-e811fc3e0a17" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_8f364657-91fa-410f-9453-fff9d834c096" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_8ce981db-2de9-44e6-804e-ffbbe1ea07d8" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_0d68c785-1c66-4b01-90b1-e811fc3e0a17" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_8ce981db-2de9-44e6-804e-ffbbe1ea07d8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_43a99447-47b0-44eb-8f71-0ca1d91c9bdc" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_0d68c785-1c66-4b01-90b1-e811fc3e0a17" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_43a99447-47b0-44eb-8f71-0ca1d91c9bdc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_0092136d-f599-46ad-a8d5-0c172ea54081" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_0d68c785-1c66-4b01-90b1-e811fc3e0a17" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_0092136d-f599-46ad-a8d5-0c172ea54081" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_ab51eab8-9c41-4377-9268-2ca4f7416b2f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_3eeca042-086d-45d2-b437-0d82c8b6d37c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8408436a-06bd-4016-b18a-42f0b0e80fa9" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_3eeca042-086d-45d2-b437-0d82c8b6d37c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_61a8b395-ad66-4c79-90df-54ca9284e527" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_3eeca042-086d-45d2-b437-0d82c8b6d37c" xlink:to="loc_us-gaap_AwardTypeAxis_61a8b395-ad66-4c79-90df-54ca9284e527" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_61a8b395-ad66-4c79-90df-54ca9284e527_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_61a8b395-ad66-4c79-90df-54ca9284e527" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_61a8b395-ad66-4c79-90df-54ca9284e527_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_54031036-4410-41d5-9d39-401b3e6730d8" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_61a8b395-ad66-4c79-90df-54ca9284e527" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_54031036-4410-41d5-9d39-401b3e6730d8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_LongTermIncentiveAwardsMember_9e9002bb-28e9-41e4-a801-e99111509de3" xlink:href="pwp-20221231.xsd#pwp_LongTermIncentiveAwardsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_54031036-4410-41d5-9d39-401b3e6730d8" xlink:to="loc_pwp_LongTermIncentiveAwardsMember_9e9002bb-28e9-41e4-a801-e99111509de3" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pwp.com/role/EquityBasedCompensationSummaryofGeneralRestrictedStockUnitsDetails" xlink:type="simple" xlink:href="pwp-20221231.xsd#EquityBasedCompensationSummaryofGeneralRestrictedStockUnitsDetails"/>
  <link:definitionLink xlink:role="http://pwp.com/role/EquityBasedCompensationSummaryofGeneralRestrictedStockUnitsDetails" xlink:type="extended" id="if2512f50e1a043edac2ef2b9f1fd1f89_EquityBasedCompensationSummaryofGeneralRestrictedStockUnitsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a3bc9156-ec18-4de3-95bb-ce245e1da6a9" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_0f1e5e4a-c8c6-4eb0-962d-ac947aa1cc43" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a3bc9156-ec18-4de3-95bb-ce245e1da6a9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_0f1e5e4a-c8c6-4eb0-962d-ac947aa1cc43" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_cac63978-adde-4cc2-b6fe-3bcccbf9ec94" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_0f1e5e4a-c8c6-4eb0-962d-ac947aa1cc43" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_cac63978-adde-4cc2-b6fe-3bcccbf9ec94" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_34b36b2d-544c-46a5-a187-729d4b877b74" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_0f1e5e4a-c8c6-4eb0-962d-ac947aa1cc43" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_34b36b2d-544c-46a5-a187-729d4b877b74" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_731e8a3f-aa96-44d6-a2df-bca2aa1111a7" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_0f1e5e4a-c8c6-4eb0-962d-ac947aa1cc43" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_731e8a3f-aa96-44d6-a2df-bca2aa1111a7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_e58458dd-ba76-4e1b-b51f-09d39f89d837" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_0f1e5e4a-c8c6-4eb0-962d-ac947aa1cc43" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_e58458dd-ba76-4e1b-b51f-09d39f89d837" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_73f6ab08-9ada-48f3-8feb-44601c6eff8c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_5116e126-e638-47d6-8b68-e5151730c966" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a3bc9156-ec18-4de3-95bb-ce245e1da6a9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_5116e126-e638-47d6-8b68-e5151730c966" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_59fa60c7-8816-4ddc-96ec-7320a663b907" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_5116e126-e638-47d6-8b68-e5151730c966" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_59fa60c7-8816-4ddc-96ec-7320a663b907" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_e48d6764-51ef-4c12-8723-b055182640e6" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_5116e126-e638-47d6-8b68-e5151730c966" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_e48d6764-51ef-4c12-8723-b055182640e6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_1ac394db-74ae-47f9-b374-d71ab322ae0b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_5116e126-e638-47d6-8b68-e5151730c966" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_1ac394db-74ae-47f9-b374-d71ab322ae0b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_ab58c88b-a89c-43a2-accb-5c52f1229a12" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_5116e126-e638-47d6-8b68-e5151730c966" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_ab58c88b-a89c-43a2-accb-5c52f1229a12" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_6d8f72ef-4542-4483-9706-87d7bb4c0488" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_2aae2264-4418-4587-a63b-0dfcd8541226" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a3bc9156-ec18-4de3-95bb-ce245e1da6a9" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_2aae2264-4418-4587-a63b-0dfcd8541226" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_183b040b-36cc-4339-b949-26ef81cc0393" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_2aae2264-4418-4587-a63b-0dfcd8541226" xlink:to="loc_us-gaap_AwardTypeAxis_183b040b-36cc-4339-b949-26ef81cc0393" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_183b040b-36cc-4339-b949-26ef81cc0393_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_183b040b-36cc-4339-b949-26ef81cc0393" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_183b040b-36cc-4339-b949-26ef81cc0393_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_964744de-b5f0-4ea6-82b2-bd3f8583fb85" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_183b040b-36cc-4339-b949-26ef81cc0393" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_964744de-b5f0-4ea6-82b2-bd3f8583fb85" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_GeneralRsusMember_86b520d6-dcd9-4028-9cc7-37664179fc47" xlink:href="pwp-20221231.xsd#pwp_GeneralRsusMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_964744de-b5f0-4ea6-82b2-bd3f8583fb85" xlink:to="loc_pwp_GeneralRsusMember_86b520d6-dcd9-4028-9cc7-37664179fc47" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pwp.com/role/EquityBasedCompensationSignificantAssumptionsDetails" xlink:type="simple" xlink:href="pwp-20221231.xsd#EquityBasedCompensationSignificantAssumptionsDetails"/>
  <link:definitionLink xlink:role="http://pwp.com/role/EquityBasedCompensationSignificantAssumptionsDetails" xlink:type="extended" id="i153605af389546f4ba666a31f384f047_EquityBasedCompensationSignificantAssumptionsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems_fc67dc24-0b21-4d61-bf79-dd1761deab48" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsMeasurementInput_6347c7ae-8f09-45eb-a4f9-c380ed26e35e" xlink:href="pwp-20221231.xsd#pwp_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsMeasurementInput"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems_fc67dc24-0b21-4d61-bf79-dd1761deab48" xlink:to="loc_pwp_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsMeasurementInput_6347c7ae-8f09-45eb-a4f9-c380ed26e35e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_accd8831-6257-4204-8946-61b632f754c9" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems_fc67dc24-0b21-4d61-bf79-dd1761deab48" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_accd8831-6257-4204-8946-61b632f754c9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_596aeb39-c914-44f7-a9dc-0a57cc1c5f5b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems_fc67dc24-0b21-4d61-bf79-dd1761deab48" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_596aeb39-c914-44f7-a9dc-0a57cc1c5f5b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_a6ff15db-cf78-4e2b-871e-ca9784f53b02" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems_fc67dc24-0b21-4d61-bf79-dd1761deab48" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_a6ff15db-cf78-4e2b-871e-ca9784f53b02" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_8ea7435b-0e89-4651-bec5-340c820697fa" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_a6ff15db-cf78-4e2b-871e-ca9784f53b02" xlink:to="loc_us-gaap_AwardTypeAxis_8ea7435b-0e89-4651-bec5-340c820697fa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_8ea7435b-0e89-4651-bec5-340c820697fa_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_8ea7435b-0e89-4651-bec5-340c820697fa" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_8ea7435b-0e89-4651-bec5-340c820697fa_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_cc61be83-070e-4d9e-b0c4-781e204b7c5a" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_8ea7435b-0e89-4651-bec5-340c820697fa" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_cc61be83-070e-4d9e-b0c4-781e204b7c5a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_LegacyAwardsMember_09202b17-60d3-4d55-9faf-65231250d97a" xlink:href="pwp-20221231.xsd#pwp_LegacyAwardsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_cc61be83-070e-4d9e-b0c4-781e204b7c5a" xlink:to="loc_pwp_LegacyAwardsMember_09202b17-60d3-4d55-9faf-65231250d97a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueAxis_d8179c5c-f077-429c-a81e-b9a58917f1c0" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ValuationTechniqueAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_a6ff15db-cf78-4e2b-871e-ca9784f53b02" xlink:to="loc_us-gaap_ValuationTechniqueAxis_d8179c5c-f077-429c-a81e-b9a58917f1c0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueDomain_d8179c5c-f077-429c-a81e-b9a58917f1c0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ValuationTechniqueDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ValuationTechniqueAxis_d8179c5c-f077-429c-a81e-b9a58917f1c0" xlink:to="loc_us-gaap_ValuationTechniqueDomain_d8179c5c-f077-429c-a81e-b9a58917f1c0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueDomain_f3b7e79f-c993-4ac6-8b80-4cceda50b7ca" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ValuationTechniqueDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ValuationTechniqueAxis_d8179c5c-f077-429c-a81e-b9a58917f1c0" xlink:to="loc_us-gaap_ValuationTechniqueDomain_f3b7e79f-c993-4ac6-8b80-4cceda50b7ca" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeApproachValuationTechniqueMember_6f4a1503-873e-4a93-91c4-9f15583c2b53" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncomeApproachValuationTechniqueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ValuationTechniqueDomain_f3b7e79f-c993-4ac6-8b80-4cceda50b7ca" xlink:to="loc_us-gaap_IncomeApproachValuationTechniqueMember_6f4a1503-873e-4a93-91c4-9f15583c2b53" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeAxis_67dd7132-4183-42f1-8d64-ebc2953e7b9d" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_MeasurementInputTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_a6ff15db-cf78-4e2b-871e-ca9784f53b02" xlink:to="loc_us-gaap_MeasurementInputTypeAxis_67dd7132-4183-42f1-8d64-ebc2953e7b9d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_67dd7132-4183-42f1-8d64-ebc2953e7b9d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_67dd7132-4183-42f1-8d64-ebc2953e7b9d" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_67dd7132-4183-42f1-8d64-ebc2953e7b9d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_6a51000f-9efa-4b1a-8048-d63c5f01ad40" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_67dd7132-4183-42f1-8d64-ebc2953e7b9d" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_6a51000f-9efa-4b1a-8048-d63c5f01ad40" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputDiscountRateMember_202aee8e-9fde-4094-8ed1-082e8a1a8000" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_MeasurementInputDiscountRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_6a51000f-9efa-4b1a-8048-d63c5f01ad40" xlink:to="loc_us-gaap_MeasurementInputDiscountRateMember_202aee8e-9fde-4094-8ed1-082e8a1a8000" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_3c6ced84-2cd7-4147-9d29-c9ce454e9d36" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_a6ff15db-cf78-4e2b-871e-ca9784f53b02" xlink:to="loc_srt_RangeAxis_3c6ced84-2cd7-4147-9d29-c9ce454e9d36" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_3c6ced84-2cd7-4147-9d29-c9ce454e9d36_default" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_3c6ced84-2cd7-4147-9d29-c9ce454e9d36" xlink:to="loc_srt_RangeMember_3c6ced84-2cd7-4147-9d29-c9ce454e9d36_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_8f62103d-fc7e-4144-bc2f-3d88e4663bed" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_3c6ced84-2cd7-4147-9d29-c9ce454e9d36" xlink:to="loc_srt_RangeMember_8f62103d-fc7e-4144-bc2f-3d88e4663bed" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_e29231ed-bc8f-4388-b5a0-aaf2835bbb80" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_8f62103d-fc7e-4144-bc2f-3d88e4663bed" xlink:to="loc_srt_MinimumMember_e29231ed-bc8f-4388-b5a0-aaf2835bbb80" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_ee3e7f84-3838-4a8c-a786-94634a572a85" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_8f62103d-fc7e-4144-bc2f-3d88e4663bed" xlink:to="loc_srt_MaximumMember_ee3e7f84-3838-4a8c-a786-94634a572a85" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pwp.com/role/EquityBasedCompensationSummaryofAwardsExpenseDetails" xlink:type="simple" xlink:href="pwp-20221231.xsd#EquityBasedCompensationSummaryofAwardsExpenseDetails"/>
  <link:definitionLink xlink:role="http://pwp.com/role/EquityBasedCompensationSummaryofAwardsExpenseDetails" xlink:type="extended" id="id392a40ec95645ccb762a224c4b63149_EquityBasedCompensationSummaryofAwardsExpenseDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_9fdf540a-802e-4bcb-96a0-e5efe2450521" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfessionalFees_aae2baa8-4e09-4c65-abab-c074d16d2c31" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ProfessionalFees"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_9fdf540a-802e-4bcb-96a0-e5efe2450521" xlink:to="loc_us-gaap_ProfessionalFees_aae2baa8-4e09-4c65-abab-c074d16d2c31" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_d4da71d1-c83f-430d-ae9d-95038cb90e39" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_9fdf540a-802e-4bcb-96a0-e5efe2450521" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_d4da71d1-c83f-430d-ae9d-95038cb90e39" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense_1ff16ffa-ee13-4130-83f9-6c4014325580" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_9fdf540a-802e-4bcb-96a0-e5efe2450521" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense_1ff16ffa-ee13-4130-83f9-6c4014325580" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_1bd6dbac-aaf2-420d-bc63-a02937cbbe44" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_9fdf540a-802e-4bcb-96a0-e5efe2450521" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_1bd6dbac-aaf2-420d-bc63-a02937cbbe44" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_e2ffbcde-9dcb-4806-96cc-36147506cbe3" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_1bd6dbac-aaf2-420d-bc63-a02937cbbe44" xlink:to="loc_us-gaap_AwardTypeAxis_e2ffbcde-9dcb-4806-96cc-36147506cbe3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_e2ffbcde-9dcb-4806-96cc-36147506cbe3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_e2ffbcde-9dcb-4806-96cc-36147506cbe3" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_e2ffbcde-9dcb-4806-96cc-36147506cbe3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_b1ded684-73f4-4dc6-ba1b-355c23ef9de6" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_e2ffbcde-9dcb-4806-96cc-36147506cbe3" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_b1ded684-73f4-4dc6-ba1b-355c23ef9de6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_IncentivePlanAwardsMember_24a13e7c-65dd-48b1-a62b-1554f8c3a787" xlink:href="pwp-20221231.xsd#pwp_IncentivePlanAwardsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_b1ded684-73f4-4dc6-ba1b-355c23ef9de6" xlink:to="loc_pwp_IncentivePlanAwardsMember_24a13e7c-65dd-48b1-a62b-1554f8c3a787" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_LegacyAwardsMember_7f65871a-108e-4fd9-90d3-87fcb560ccaa" xlink:href="pwp-20221231.xsd#pwp_LegacyAwardsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_b1ded684-73f4-4dc6-ba1b-355c23ef9de6" xlink:to="loc_pwp_LegacyAwardsMember_7f65871a-108e-4fd9-90d3-87fcb560ccaa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_ProfessionalPartnersAwardMember_a50523bb-e103-4626-b6e4-51f07cac0320" xlink:href="pwp-20221231.xsd#pwp_ProfessionalPartnersAwardMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_b1ded684-73f4-4dc6-ba1b-355c23ef9de6" xlink:to="loc_pwp_ProfessionalPartnersAwardMember_a50523bb-e103-4626-b6e4-51f07cac0320" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pwp.com/role/OtherCompensationandBenefitsAdditionalInformationDetails" xlink:type="simple" xlink:href="pwp-20221231.xsd#OtherCompensationandBenefitsAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://pwp.com/role/OtherCompensationandBenefitsAdditionalInformationDetails" xlink:type="extended" id="i616648345382427db7dbd44f2799b61b_OtherCompensationandBenefitsAdditionalInformationDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1c9f8945-4ddd-4b49-8952-36aba1cb4b84" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_RelatedPartyTransactionPartnerPromissoryNotes_8d560b7e-8a43-438a-8621-dacf3b3193bc" xlink:href="pwp-20221231.xsd#pwp_RelatedPartyTransactionPartnerPromissoryNotes"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1c9f8945-4ddd-4b49-8952-36aba1cb4b84" xlink:to="loc_pwp_RelatedPartyTransactionPartnerPromissoryNotes_8d560b7e-8a43-438a-8621-dacf3b3193bc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_NonCashPaydownOfPartnerPromissoryNotes_c4126f9c-140b-44cd-984a-e182f0d2148c" xlink:href="pwp-20221231.xsd#pwp_NonCashPaydownOfPartnerPromissoryNotes"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1c9f8945-4ddd-4b49-8952-36aba1cb4b84" xlink:to="loc_pwp_NonCashPaydownOfPartnerPromissoryNotes_c4126f9c-140b-44cd-984a-e182f0d2148c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromRelatedPartyDebt_3a40cbda-4915-4541-8443-839f84e28f92" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ProceedsFromRelatedPartyDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1c9f8945-4ddd-4b49-8952-36aba1cb4b84" xlink:to="loc_us-gaap_ProceedsFromRelatedPartyDebt_3a40cbda-4915-4541-8443-839f84e28f92" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_bd3f880b-2f53-4a1c-9383-ee156dea6371" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1c9f8945-4ddd-4b49-8952-36aba1cb4b84" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_bd3f880b-2f53-4a1c-9383-ee156dea6371" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DueFromRelatedParties_77d973f4-2554-4860-be88-e253712baea7" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DueFromRelatedParties"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1c9f8945-4ddd-4b49-8952-36aba1cb4b84" xlink:to="loc_us-gaap_DueFromRelatedParties_77d973f4-2554-4860-be88-e253712baea7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty_29aae94b-eb4c-4dc5-8c4d-96402016c3a8" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1c9f8945-4ddd-4b49-8952-36aba1cb4b84" xlink:to="loc_us-gaap_RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty_29aae94b-eb4c-4dc5-8c4d-96402016c3a8" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionOtherRevenuesFromTransactionsWithRelatedParty_9b7db155-1335-41c5-8ad3-224a9a1071de" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RelatedPartyTransactionOtherRevenuesFromTransactionsWithRelatedParty"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1c9f8945-4ddd-4b49-8952-36aba1cb4b84" xlink:to="loc_us-gaap_RelatedPartyTransactionOtherRevenuesFromTransactionsWithRelatedParty_9b7db155-1335-41c5-8ad3-224a9a1071de" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_da645f04-1a67-4c8c-a7c8-d05f7e3e9e3b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1c9f8945-4ddd-4b49-8952-36aba1cb4b84" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_da645f04-1a67-4c8c-a7c8-d05f7e3e9e3b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_2db9115d-b65b-4a41-9b65-16ec185dc00d" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_da645f04-1a67-4c8c-a7c8-d05f7e3e9e3b" xlink:to="loc_us-gaap_DebtInstrumentAxis_2db9115d-b65b-4a41-9b65-16ec185dc00d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_2db9115d-b65b-4a41-9b65-16ec185dc00d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_2db9115d-b65b-4a41-9b65-16ec185dc00d" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_2db9115d-b65b-4a41-9b65-16ec185dc00d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_8aad3a6e-2db7-425c-8abe-6035bec49119" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_2db9115d-b65b-4a41-9b65-16ec185dc00d" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_8aad3a6e-2db7-425c-8abe-6035bec49119" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_PartnerPromissoryNotesMember_cebebc12-11b1-4cd5-9473-bde1867946d9" xlink:href="pwp-20221231.xsd#pwp_PartnerPromissoryNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_8aad3a6e-2db7-425c-8abe-6035bec49119" xlink:to="loc_pwp_PartnerPromissoryNotesMember_cebebc12-11b1-4cd5-9473-bde1867946d9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_da5a5600-9f26-43b6-862a-b0bd95274578" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_da645f04-1a67-4c8c-a7c8-d05f7e3e9e3b" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_da5a5600-9f26-43b6-862a-b0bd95274578" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_da5a5600-9f26-43b6-862a-b0bd95274578_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_da5a5600-9f26-43b6-862a-b0bd95274578" xlink:to="loc_us-gaap_RelatedPartyDomain_da5a5600-9f26-43b6-862a-b0bd95274578_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_ec085faf-f517-4963-85ac-aa4dbdba7137" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_da5a5600-9f26-43b6-862a-b0bd95274578" xlink:to="loc_us-gaap_RelatedPartyDomain_ec085faf-f517-4963-85ac-aa4dbdba7137" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_PartnersMember_96642ae9-f908-4390-8f6a-1384197b500d" xlink:href="pwp-20221231.xsd#pwp_PartnersMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_ec085faf-f517-4963-85ac-aa4dbdba7137" xlink:to="loc_pwp_PartnersMember_96642ae9-f908-4390-8f6a-1384197b500d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_EntityControlledByDirectorMember_39a491bc-3a41-4fed-b7f8-403e04d84e15" xlink:href="pwp-20221231.xsd#pwp_EntityControlledByDirectorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_ec085faf-f517-4963-85ac-aa4dbdba7137" xlink:to="loc_pwp_EntityControlledByDirectorMember_39a491bc-3a41-4fed-b7f8-403e04d84e15" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_PFACHoldingsMember_d8d04fef-2076-4064-9644-aaeb915c1306" xlink:href="pwp-20221231.xsd#pwp_PFACHoldingsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_ec085faf-f517-4963-85ac-aa4dbdba7137" xlink:to="loc_pwp_PFACHoldingsMember_d8d04fef-2076-4064-9644-aaeb915c1306" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_01d09edc-c49a-40ff-9df9-e2fa202e1f56" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_da645f04-1a67-4c8c-a7c8-d05f7e3e9e3b" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_01d09edc-c49a-40ff-9df9-e2fa202e1f56" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_01d09edc-c49a-40ff-9df9-e2fa202e1f56_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_01d09edc-c49a-40ff-9df9-e2fa202e1f56" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_01d09edc-c49a-40ff-9df9-e2fa202e1f56_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_7082cd80-6040-42b5-8b56-760ee532a1cf" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_01d09edc-c49a-40ff-9df9-e2fa202e1f56" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_7082cd80-6040-42b5-8b56-760ee532a1cf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConvertibleDebtMember_8c5c80e0-6d40-47e5-943d-3d8d6c1350f0" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ConvertibleDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_7082cd80-6040-42b5-8b56-760ee532a1cf" xlink:to="loc_us-gaap_ConvertibleDebtMember_8c5c80e0-6d40-47e5-943d-3d8d6c1350f0" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pwp.com/role/NetIncomeLossPerShareAttributabletoClassACommonShareholdersScheduleofWeightedAveragePotentiallyDilutiveSharesExcludedfromComputationofDilutedNetIncomeLossPerShareDetails" xlink:type="simple" xlink:href="pwp-20221231.xsd#NetIncomeLossPerShareAttributabletoClassACommonShareholdersScheduleofWeightedAveragePotentiallyDilutiveSharesExcludedfromComputationofDilutedNetIncomeLossPerShareDetails"/>
  <link:definitionLink xlink:role="http://pwp.com/role/NetIncomeLossPerShareAttributabletoClassACommonShareholdersScheduleofWeightedAveragePotentiallyDilutiveSharesExcludedfromComputationofDilutedNetIncomeLossPerShareDetails" xlink:type="extended" id="icdef92eb0d384919b0d2732037a6e920_NetIncomeLossPerShareAttributabletoClassACommonShareholdersScheduleofWeightedAveragePotentiallyDilutiveSharesExcludedfromComputationofDilutedNetIncomeLossPerShareDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_af7501a4-9703-4871-a5d6-b8689b81040e" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_fb8d1e14-49c9-4e49-a27a-90f9b4c0ec78" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_af7501a4-9703-4871-a5d6-b8689b81040e" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_fb8d1e14-49c9-4e49-a27a-90f9b4c0ec78" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_448a667b-7da8-4046-9153-902e62fd379b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_af7501a4-9703-4871-a5d6-b8689b81040e" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_448a667b-7da8-4046-9153-902e62fd379b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_d10ee89b-7f6c-4549-8f8d-e9163c5645fb" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_448a667b-7da8-4046-9153-902e62fd379b" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_d10ee89b-7f6c-4549-8f8d-e9163c5645fb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_d10ee89b-7f6c-4549-8f8d-e9163c5645fb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_d10ee89b-7f6c-4549-8f8d-e9163c5645fb" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_d10ee89b-7f6c-4549-8f8d-e9163c5645fb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_84efff03-e010-4061-a6cd-d9d43398ed21" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_d10ee89b-7f6c-4549-8f8d-e9163c5645fb" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_84efff03-e010-4061-a6cd-d9d43398ed21" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WarrantMember_3f1d158e-2e0f-4b93-b73c-280aaef16e06" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_WarrantMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_84efff03-e010-4061-a6cd-d9d43398ed21" xlink:to="loc_us-gaap_WarrantMember_3f1d158e-2e0f-4b93-b73c-280aaef16e06" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_IncentivePlanAwardsMember_d1b2bef7-8dee-48c5-a819-6f6a7afaffdf" xlink:href="pwp-20221231.xsd#pwp_IncentivePlanAwardsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_84efff03-e010-4061-a6cd-d9d43398ed21" xlink:to="loc_pwp_IncentivePlanAwardsMember_d1b2bef7-8dee-48c5-a819-6f6a7afaffdf" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pwp.com/role/FairValueMeasurementsandInvestmentsScheduleofAssetsandLiabilitiesMeasuredatFairValueonRecurringBasisDetails" xlink:type="simple" xlink:href="pwp-20221231.xsd#FairValueMeasurementsandInvestmentsScheduleofAssetsandLiabilitiesMeasuredatFairValueonRecurringBasisDetails"/>
  <link:definitionLink xlink:role="http://pwp.com/role/FairValueMeasurementsandInvestmentsScheduleofAssetsandLiabilitiesMeasuredatFairValueonRecurringBasisDetails" xlink:type="extended" id="i0656c9c7aa454052948c792f932ab65e_FairValueMeasurementsandInvestmentsScheduleofAssetsandLiabilitiesMeasuredatFairValueonRecurringBasisDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_cda56cf5-9ff2-425f-bb76-63c8d8ba513f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentsFairValueDisclosure_9199ddbf-21ff-4c8e-8dab-ab490824998a" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_InvestmentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_cda56cf5-9ff2-425f-bb76-63c8d8ba513f" xlink:to="loc_us-gaap_InvestmentsFairValueDisclosure_9199ddbf-21ff-4c8e-8dab-ab490824998a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashSurrenderValueFairValueDisclosure_6ae68d71-8815-4761-acc9-74e8621c4914" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CashSurrenderValueFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_cda56cf5-9ff2-425f-bb76-63c8d8ba513f" xlink:to="loc_us-gaap_CashSurrenderValueFairValueDisclosure_6ae68d71-8815-4761-acc9-74e8621c4914" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_cd01a03e-249a-482b-91a4-ac8658706395" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AssetsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_cda56cf5-9ff2-425f-bb76-63c8d8ba513f" xlink:to="loc_us-gaap_AssetsFairValueDisclosure_cd01a03e-249a-482b-91a4-ac8658706395" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilities_64de97f4-f1dc-428a-adfc-eb0a6fe8037c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_cda56cf5-9ff2-425f-bb76-63c8d8ba513f" xlink:to="loc_us-gaap_DerivativeLiabilities_64de97f4-f1dc-428a-adfc-eb0a6fe8037c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialLiabilitiesFairValueDisclosure_f671a9a9-c6e8-4058-bda7-81e343854c65" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FinancialLiabilitiesFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_cda56cf5-9ff2-425f-bb76-63c8d8ba513f" xlink:to="loc_us-gaap_FinancialLiabilitiesFairValueDisclosure_f671a9a9-c6e8-4058-bda7-81e343854c65" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_c2dcabbf-8a9e-426e-b6ef-08309445ad29" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_cda56cf5-9ff2-425f-bb76-63c8d8ba513f" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_c2dcabbf-8a9e-426e-b6ef-08309445ad29" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_64324477-0ff2-4b0e-8e90-9f6aa4684109" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_c2dcabbf-8a9e-426e-b6ef-08309445ad29" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_64324477-0ff2-4b0e-8e90-9f6aa4684109" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_64324477-0ff2-4b0e-8e90-9f6aa4684109_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_64324477-0ff2-4b0e-8e90-9f6aa4684109" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_64324477-0ff2-4b0e-8e90-9f6aa4684109_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_ef72d789-5da4-459b-ae81-a283db6105f0" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_64324477-0ff2-4b0e-8e90-9f6aa4684109" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_ef72d789-5da4-459b-ae81-a283db6105f0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_68b34ebe-02f5-4757-9da8-0fd9ae9c85d3" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_ef72d789-5da4-459b-ae81-a283db6105f0" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_68b34ebe-02f5-4757-9da8-0fd9ae9c85d3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_39f1b70e-7a00-4319-a283-7e920ea5ea3f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_ef72d789-5da4-459b-ae81-a283db6105f0" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_39f1b70e-7a00-4319-a283-7e920ea5ea3f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_3775b3f0-a645-4762-a47f-3074a11d6a5f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_ef72d789-5da4-459b-ae81-a283db6105f0" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_3775b3f0-a645-4762-a47f-3074a11d6a5f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightAxis_3bd462c1-d319-4fd0-a825-823e26026f0e" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfWarrantOrRightAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_c2dcabbf-8a9e-426e-b6ef-08309445ad29" xlink:to="loc_us-gaap_ClassOfWarrantOrRightAxis_3bd462c1-d319-4fd0-a825-823e26026f0e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightDomain_3bd462c1-d319-4fd0-a825-823e26026f0e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfWarrantOrRightDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ClassOfWarrantOrRightAxis_3bd462c1-d319-4fd0-a825-823e26026f0e" xlink:to="loc_us-gaap_ClassOfWarrantOrRightDomain_3bd462c1-d319-4fd0-a825-823e26026f0e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightDomain_a5b0c6f9-27ce-4add-9241-ff6fcd9550f0" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfWarrantOrRightDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ClassOfWarrantOrRightAxis_3bd462c1-d319-4fd0-a825-823e26026f0e" xlink:to="loc_us-gaap_ClassOfWarrantOrRightDomain_a5b0c6f9-27ce-4add-9241-ff6fcd9550f0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_PublicWarrantsMember_f3deb6b1-0fb9-4950-82b4-fc58d51b8ef9" xlink:href="pwp-20221231.xsd#pwp_PublicWarrantsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightDomain_a5b0c6f9-27ce-4add-9241-ff6fcd9550f0" xlink:to="loc_pwp_PublicWarrantsMember_f3deb6b1-0fb9-4950-82b4-fc58d51b8ef9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_PrivateWarrantsMember_75b51ba7-b86b-429e-8dfd-6d3bfb8c6a77" xlink:href="pwp-20221231.xsd#pwp_PrivateWarrantsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightDomain_a5b0c6f9-27ce-4add-9241-ff6fcd9550f0" xlink:to="loc_pwp_PrivateWarrantsMember_75b51ba7-b86b-429e-8dfd-6d3bfb8c6a77" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_22a85cc4-e14e-446e-9f06-e8943191acb3" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_c2dcabbf-8a9e-426e-b6ef-08309445ad29" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_22a85cc4-e14e-446e-9f06-e8943191acb3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_22a85cc4-e14e-446e-9f06-e8943191acb3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_22a85cc4-e14e-446e-9f06-e8943191acb3" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_22a85cc4-e14e-446e-9f06-e8943191acb3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_08fca24b-d13e-4e61-b96a-d45946042fc7" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_22a85cc4-e14e-446e-9f06-e8943191acb3" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_08fca24b-d13e-4e61-b96a-d45946042fc7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_a3654c3b-546c-4c4a-8965-5a19a32ceeef" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_08fca24b-d13e-4e61-b96a-d45946042fc7" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_a3654c3b-546c-4c4a-8965-5a19a32ceeef" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pwp.com/role/FairValueMeasurementsandInvestmentsAdditionalInformationDetails" xlink:type="simple" xlink:href="pwp-20221231.xsd#FairValueMeasurementsandInvestmentsAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://pwp.com/role/FairValueMeasurementsandInvestmentsAdditionalInformationDetails" xlink:type="extended" id="ida66bf2197d24ac3b9d44224351fd624_FairValueMeasurementsandInvestmentsAdditionalInformationDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_71c44ac6-81c6-4fa1-841b-31b96e9aa94f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentOwnedAtCost_380aeb45-a168-4886-8c03-586071897fdd" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_InvestmentOwnedAtCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_71c44ac6-81c6-4fa1-841b-31b96e9aa94f" xlink:to="loc_us-gaap_InvestmentOwnedAtCost_380aeb45-a168-4886-8c03-586071897fdd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesGainLoss_549bc40e-08f5-408a-8967-a14389b2bf5d" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtSecuritiesGainLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_71c44ac6-81c6-4fa1-841b-31b96e9aa94f" xlink:to="loc_us-gaap_DebtSecuritiesGainLoss_549bc40e-08f5-408a-8967-a14389b2bf5d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_WarrantsAndRightsOutstandingFairValueAssumptionsExpectedDividendRate_65cabd23-edfd-4f53-8411-3cfb5a38e62c" xlink:href="pwp-20221231.xsd#pwp_WarrantsAndRightsOutstandingFairValueAssumptionsExpectedDividendRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_71c44ac6-81c6-4fa1-841b-31b96e9aa94f" xlink:to="loc_pwp_WarrantsAndRightsOutstandingFairValueAssumptionsExpectedDividendRate_65cabd23-edfd-4f53-8411-3cfb5a38e62c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_WarrantsAndRightsOutstandingFairValueAssumptionsExpectedVolatilityRate_493ff87d-dc8b-4dad-bbf6-bbb9686a450f" xlink:href="pwp-20221231.xsd#pwp_WarrantsAndRightsOutstandingFairValueAssumptionsExpectedVolatilityRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_71c44ac6-81c6-4fa1-841b-31b96e9aa94f" xlink:to="loc_pwp_WarrantsAndRightsOutstandingFairValueAssumptionsExpectedVolatilityRate_493ff87d-dc8b-4dad-bbf6-bbb9686a450f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestments_638148ab-b721-4174-971d-07d55d32dfc9" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityMethodInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_71c44ac6-81c6-4fa1-841b-31b96e9aa94f" xlink:to="loc_us-gaap_EquityMethodInvestments_638148ab-b721-4174-971d-07d55d32dfc9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentRealizedGainLossOnDisposal_2379d553-4b9b-430f-b6ed-471aca613c56" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityMethodInvestmentRealizedGainLossOnDisposal"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_71c44ac6-81c6-4fa1-841b-31b96e9aa94f" xlink:to="loc_us-gaap_EquityMethodInvestmentRealizedGainLossOnDisposal_2379d553-4b9b-430f-b6ed-471aca613c56" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentAggregateCost_1caf3822-21c5-4e1f-97fb-8bd3cf876f64" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityMethodInvestmentAggregateCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_71c44ac6-81c6-4fa1-841b-31b96e9aa94f" xlink:to="loc_us-gaap_EquityMethodInvestmentAggregateCost_1caf3822-21c5-4e1f-97fb-8bd3cf876f64" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_84bc2c3b-4a71-4561-843e-ae705e7d90c2" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_71c44ac6-81c6-4fa1-841b-31b96e9aa94f" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_84bc2c3b-4a71-4561-843e-ae705e7d90c2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightAxis_a0e9f177-a068-461c-a47b-8c8f4f9bb235" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfWarrantOrRightAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_84bc2c3b-4a71-4561-843e-ae705e7d90c2" xlink:to="loc_us-gaap_ClassOfWarrantOrRightAxis_a0e9f177-a068-461c-a47b-8c8f4f9bb235" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightDomain_a0e9f177-a068-461c-a47b-8c8f4f9bb235_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfWarrantOrRightDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ClassOfWarrantOrRightAxis_a0e9f177-a068-461c-a47b-8c8f4f9bb235" xlink:to="loc_us-gaap_ClassOfWarrantOrRightDomain_a0e9f177-a068-461c-a47b-8c8f4f9bb235_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightDomain_714efbf0-fced-4017-bcaa-029c55fff683" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfWarrantOrRightDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ClassOfWarrantOrRightAxis_a0e9f177-a068-461c-a47b-8c8f4f9bb235" xlink:to="loc_us-gaap_ClassOfWarrantOrRightDomain_714efbf0-fced-4017-bcaa-029c55fff683" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_PublicWarrantsMember_55892c1a-80bc-4eae-a9d9-aeb89b8734ed" xlink:href="pwp-20221231.xsd#pwp_PublicWarrantsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightDomain_714efbf0-fced-4017-bcaa-029c55fff683" xlink:to="loc_pwp_PublicWarrantsMember_55892c1a-80bc-4eae-a9d9-aeb89b8734ed" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_PrivateWarrantsMember_a25e7004-8416-482c-bf75-de43e6ccd276" xlink:href="pwp-20221231.xsd#pwp_PrivateWarrantsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightDomain_714efbf0-fced-4017-bcaa-029c55fff683" xlink:to="loc_pwp_PrivateWarrantsMember_a25e7004-8416-482c-bf75-de43e6ccd276" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pwp.com/role/FairValueMeasurementsandInvestmentsScheduleofChangesinLevel3LiabilitiesmeasuredatFairValueDetails" xlink:type="simple" xlink:href="pwp-20221231.xsd#FairValueMeasurementsandInvestmentsScheduleofChangesinLevel3LiabilitiesmeasuredatFairValueDetails"/>
  <link:definitionLink xlink:role="http://pwp.com/role/FairValueMeasurementsandInvestmentsScheduleofChangesinLevel3LiabilitiesmeasuredatFairValueDetails" xlink:type="extended" id="i1e14b61cfaca47bfb3855f2971f82b52_FairValueMeasurementsandInvestmentsScheduleofChangesinLevel3LiabilitiesmeasuredatFairValueDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_755ec123-dc52-4597-b8be-d294e2ab74c8" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue_96a78e7b-1181-49b8-be0b-8377aef390ce" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_755ec123-dc52-4597-b8be-d294e2ab74c8" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue_96a78e7b-1181-49b8-be0b-8377aef390ce" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityPeriodIncreaseDecrease_6c8a435b-4993-4160-9e88-1b82d1ea2f88" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityPeriodIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_755ec123-dc52-4597-b8be-d294e2ab74c8" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityPeriodIncreaseDecrease_6c8a435b-4993-4160-9e88-1b82d1ea2f88" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements_781022e0-3bc2-4a34-aa28-1701ec6c01d5" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_755ec123-dc52-4597-b8be-d294e2ab74c8" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements_781022e0-3bc2-4a34-aa28-1701ec6c01d5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue_8d23f0f4-884d-4645-bd96-dd4febbc98fb" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTable_4cd06c95-9999-48b1-b8e8-d24d01c7fa2d" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_755ec123-dc52-4597-b8be-d294e2ab74c8" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTable_4cd06c95-9999-48b1-b8e8-d24d01c7fa2d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_4fd9c1c7-af66-47f0-aa04-c2e7c9f589c4" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTable_4cd06c95-9999-48b1-b8e8-d24d01c7fa2d" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_4fd9c1c7-af66-47f0-aa04-c2e7c9f589c4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_4fd9c1c7-af66-47f0-aa04-c2e7c9f589c4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_4fd9c1c7-af66-47f0-aa04-c2e7c9f589c4" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_4fd9c1c7-af66-47f0-aa04-c2e7c9f589c4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_3ce2b10e-de65-4d74-98de-82770d8ade92" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_4fd9c1c7-af66-47f0-aa04-c2e7c9f589c4" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_3ce2b10e-de65-4d74-98de-82770d8ade92" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_b706872b-d9d4-4e7a-97ac-6c0d79e8834a" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_3ce2b10e-de65-4d74-98de-82770d8ade92" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_b706872b-d9d4-4e7a-97ac-6c0d79e8834a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightAxis_e4f123ba-916a-4b3a-ab3c-d7987cc4c57c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfWarrantOrRightAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTable_4cd06c95-9999-48b1-b8e8-d24d01c7fa2d" xlink:to="loc_us-gaap_ClassOfWarrantOrRightAxis_e4f123ba-916a-4b3a-ab3c-d7987cc4c57c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightDomain_e4f123ba-916a-4b3a-ab3c-d7987cc4c57c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfWarrantOrRightDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ClassOfWarrantOrRightAxis_e4f123ba-916a-4b3a-ab3c-d7987cc4c57c" xlink:to="loc_us-gaap_ClassOfWarrantOrRightDomain_e4f123ba-916a-4b3a-ab3c-d7987cc4c57c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightDomain_0d7ea551-7e4b-4631-ae54-777a46be284b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfWarrantOrRightDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ClassOfWarrantOrRightAxis_e4f123ba-916a-4b3a-ab3c-d7987cc4c57c" xlink:to="loc_us-gaap_ClassOfWarrantOrRightDomain_0d7ea551-7e4b-4631-ae54-777a46be284b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_PrivateWarrantsMember_fbe781dc-bc75-48f7-bdec-48f2186cc3af" xlink:href="pwp-20221231.xsd#pwp_PrivateWarrantsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightDomain_0d7ea551-7e4b-4631-ae54-777a46be284b" xlink:to="loc_pwp_PrivateWarrantsMember_fbe781dc-bc75-48f7-bdec-48f2186cc3af" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pwp.com/role/RelatedPartyTransactionsScheduleofComponentsofRelatedPartyRevenuesandExpensesDetails" xlink:type="simple" xlink:href="pwp-20221231.xsd#RelatedPartyTransactionsScheduleofComponentsofRelatedPartyRevenuesandExpensesDetails"/>
  <link:definitionLink xlink:role="http://pwp.com/role/RelatedPartyTransactionsScheduleofComponentsofRelatedPartyRevenuesandExpensesDetails" xlink:type="extended" id="i1fa11fed2dfd46e5a128f92da3d71e78_RelatedPartyTransactionsScheduleofComponentsofRelatedPartyRevenuesandExpensesDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionLineItems_d091f8b0-689e-4fd1-ba71-7310f3df89f3" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RelatedPartyTransactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_RelatedPartyIncomeAbstract_04f3eed1-97b9-46f7-b1e8-6112c2cf6c99" xlink:href="pwp-20221231.xsd#pwp_RelatedPartyIncomeAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_d091f8b0-689e-4fd1-ba71-7310f3df89f3" xlink:to="loc_pwp_RelatedPartyIncomeAbstract_04f3eed1-97b9-46f7-b1e8-6112c2cf6c99" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionOtherRevenuesFromTransactionsWithRelatedParty_e86f4ab6-4344-41d2-ad55-82f5c8a22285" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RelatedPartyTransactionOtherRevenuesFromTransactionsWithRelatedParty"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pwp_RelatedPartyIncomeAbstract_04f3eed1-97b9-46f7-b1e8-6112c2cf6c99" xlink:to="loc_us-gaap_RelatedPartyTransactionOtherRevenuesFromTransactionsWithRelatedParty_e86f4ab6-4344-41d2-ad55-82f5c8a22285" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubleaseIncome_81beea6a-92b2-4a76-b070-6015458e6f52" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SubleaseIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pwp_RelatedPartyIncomeAbstract_04f3eed1-97b9-46f7-b1e8-6112c2cf6c99" xlink:to="loc_us-gaap_SubleaseIncome_81beea6a-92b2-4a76-b070-6015458e6f52" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_7c525ca3-9ba7-4e61-aaa6-8745f1322892" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_d091f8b0-689e-4fd1-ba71-7310f3df89f3" xlink:to="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_7c525ca3-9ba7-4e61-aaa6-8745f1322892" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_de96e81b-a8c8-410d-91ae-aa25b7d99a24" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_7c525ca3-9ba7-4e61-aaa6-8745f1322892" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_de96e81b-a8c8-410d-91ae-aa25b7d99a24" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_de96e81b-a8c8-410d-91ae-aa25b7d99a24_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_de96e81b-a8c8-410d-91ae-aa25b7d99a24" xlink:to="loc_us-gaap_RelatedPartyDomain_de96e81b-a8c8-410d-91ae-aa25b7d99a24_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_b42e2b1c-91a1-4adb-8ecd-5f7f66c59303" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_de96e81b-a8c8-410d-91ae-aa25b7d99a24" xlink:to="loc_us-gaap_RelatedPartyDomain_b42e2b1c-91a1-4adb-8ecd-5f7f66c59303" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_TSACompensationRelatedMember_7a4340b9-5745-461c-be4c-16d613034f3d" xlink:href="pwp-20221231.xsd#pwp_TSACompensationRelatedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_b42e2b1c-91a1-4adb-8ecd-5f7f66c59303" xlink:to="loc_pwp_TSACompensationRelatedMember_7a4340b9-5745-461c-be4c-16d613034f3d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_TSANonCompensationRelatedMember_f3d919af-f436-41ec-b67b-c21606ab9526" xlink:href="pwp-20221231.xsd#pwp_TSANonCompensationRelatedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_b42e2b1c-91a1-4adb-8ecd-5f7f66c59303" xlink:to="loc_pwp_TSANonCompensationRelatedMember_f3d919af-f436-41ec-b67b-c21606ab9526" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_TsaMember_70162278-c407-44be-8281-efc5b05d4986" xlink:href="pwp-20221231.xsd#pwp_TsaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_b42e2b1c-91a1-4adb-8ecd-5f7f66c59303" xlink:to="loc_pwp_TsaMember_70162278-c407-44be-8281-efc5b05d4986" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pwp.com/role/RelatedPartyTransactionsAdditionalInformationDetails" xlink:type="simple" xlink:href="pwp-20221231.xsd#RelatedPartyTransactionsAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://pwp.com/role/RelatedPartyTransactionsAdditionalInformationDetails" xlink:type="extended" id="i1e9cdbf05f0d4eeb8a486b7a9880c1e4_RelatedPartyTransactionsAdditionalInformationDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionLineItems_f6c4bc94-9fd7-481b-a7b2-7c379632769d" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RelatedPartyTransactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_TaxReceivableAgreementTaxSavingsPercentage_97ecb3c9-c52c-4a63-b8d5-bf8155df3430" xlink:href="pwp-20221231.xsd#pwp_TaxReceivableAgreementTaxSavingsPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_f6c4bc94-9fd7-481b-a7b2-7c379632769d" xlink:to="loc_pwp_TaxReceivableAgreementTaxSavingsPercentage_97ecb3c9-c52c-4a63-b8d5-bf8155df3430" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_AmountDuePursuantToTaxReceivableAgreement_61d662d6-c940-4b32-8a27-05fbcb4f96b0" xlink:href="pwp-20221231.xsd#pwp_AmountDuePursuantToTaxReceivableAgreement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_f6c4bc94-9fd7-481b-a7b2-7c379632769d" xlink:to="loc_pwp_AmountDuePursuantToTaxReceivableAgreement_61d662d6-c940-4b32-8a27-05fbcb4f96b0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_RelatedPartyTransactionPartnerPromissoryNotes_0d0b1f36-c679-4257-9295-5b33bf8ff01c" xlink:href="pwp-20221231.xsd#pwp_RelatedPartyTransactionPartnerPromissoryNotes"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_f6c4bc94-9fd7-481b-a7b2-7c379632769d" xlink:to="loc_pwp_RelatedPartyTransactionPartnerPromissoryNotes_0d0b1f36-c679-4257-9295-5b33bf8ff01c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromRelatedPartyDebt_439892df-2e2f-439d-9400-30ca040ac206" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ProceedsFromRelatedPartyDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_f6c4bc94-9fd7-481b-a7b2-7c379632769d" xlink:to="loc_us-gaap_ProceedsFromRelatedPartyDebt_439892df-2e2f-439d-9400-30ca040ac206" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DueFromRelatedParties_da1a8e18-805e-4360-950f-1aab3f0af619" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DueFromRelatedParties"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_f6c4bc94-9fd7-481b-a7b2-7c379632769d" xlink:to="loc_us-gaap_DueFromRelatedParties_da1a8e18-805e-4360-950f-1aab3f0af619" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_6d34c51f-210f-41fa-bf08-c03452c6cf29" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_f6c4bc94-9fd7-481b-a7b2-7c379632769d" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_6d34c51f-210f-41fa-bf08-c03452c6cf29" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty_f47224da-7cc7-40b8-982a-9a1ea868163c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_f6c4bc94-9fd7-481b-a7b2-7c379632769d" xlink:to="loc_us-gaap_RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty_f47224da-7cc7-40b8-982a-9a1ea868163c" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionOtherRevenuesFromTransactionsWithRelatedParty_1a200d45-7fa9-40eb-9467-a74a6149f8d3" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RelatedPartyTransactionOtherRevenuesFromTransactionsWithRelatedParty"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_f6c4bc94-9fd7-481b-a7b2-7c379632769d" xlink:to="loc_us-gaap_RelatedPartyTransactionOtherRevenuesFromTransactionsWithRelatedParty_1a200d45-7fa9-40eb-9467-a74a6149f8d3" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_6a6c94d8-d44b-4e31-a67e-7a1c68f60085" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_f6c4bc94-9fd7-481b-a7b2-7c379632769d" xlink:to="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_6a6c94d8-d44b-4e31-a67e-7a1c68f60085" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_0d09c158-f8e9-493d-bf92-a026381ebfef" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_6a6c94d8-d44b-4e31-a67e-7a1c68f60085" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_0d09c158-f8e9-493d-bf92-a026381ebfef" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_0d09c158-f8e9-493d-bf92-a026381ebfef_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_0d09c158-f8e9-493d-bf92-a026381ebfef" xlink:to="loc_us-gaap_RelatedPartyDomain_0d09c158-f8e9-493d-bf92-a026381ebfef_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_6f418d34-5dae-4f52-bfeb-1dba76cb722a" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_0d09c158-f8e9-493d-bf92-a026381ebfef" xlink:to="loc_us-gaap_RelatedPartyDomain_6f418d34-5dae-4f52-bfeb-1dba76cb722a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_PartnersMember_18f5e8e3-a4fa-4f3d-846f-25ce19a970a9" xlink:href="pwp-20221231.xsd#pwp_PartnersMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_6f418d34-5dae-4f52-bfeb-1dba76cb722a" xlink:to="loc_pwp_PartnersMember_18f5e8e3-a4fa-4f3d-846f-25ce19a970a9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_PFACHoldingsMember_ec813e8c-9f81-4469-a2d7-81e9e43f0bfb" xlink:href="pwp-20221231.xsd#pwp_PFACHoldingsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_6f418d34-5dae-4f52-bfeb-1dba76cb722a" xlink:to="loc_pwp_PFACHoldingsMember_ec813e8c-9f81-4469-a2d7-81e9e43f0bfb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_EntityControlledByDirectorMember_09b07801-bc11-426a-978e-d5d527b0a530" xlink:href="pwp-20221231.xsd#pwp_EntityControlledByDirectorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_6f418d34-5dae-4f52-bfeb-1dba76cb722a" xlink:to="loc_pwp_EntityControlledByDirectorMember_09b07801-bc11-426a-978e-d5d527b0a530" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_7789c5f1-4cc1-42c3-bc4f-fe69f006ac9c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_6a6c94d8-d44b-4e31-a67e-7a1c68f60085" xlink:to="loc_us-gaap_DebtInstrumentAxis_7789c5f1-4cc1-42c3-bc4f-fe69f006ac9c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_7789c5f1-4cc1-42c3-bc4f-fe69f006ac9c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_7789c5f1-4cc1-42c3-bc4f-fe69f006ac9c" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_7789c5f1-4cc1-42c3-bc4f-fe69f006ac9c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_d897cc53-3a44-4f06-a959-c8b03ab23391" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_7789c5f1-4cc1-42c3-bc4f-fe69f006ac9c" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_d897cc53-3a44-4f06-a959-c8b03ab23391" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_PartnerPromissoryNotesMember_7ae3c618-42fe-49ff-9578-fe74f2ccb050" xlink:href="pwp-20221231.xsd#pwp_PartnerPromissoryNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_d897cc53-3a44-4f06-a959-c8b03ab23391" xlink:to="loc_pwp_PartnerPromissoryNotesMember_7ae3c618-42fe-49ff-9578-fe74f2ccb050" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_9b7ea47a-64f8-48b9-b992-56789b0dfe7e" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_6a6c94d8-d44b-4e31-a67e-7a1c68f60085" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_9b7ea47a-64f8-48b9-b992-56789b0dfe7e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_9b7ea47a-64f8-48b9-b992-56789b0dfe7e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_9b7ea47a-64f8-48b9-b992-56789b0dfe7e" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_9b7ea47a-64f8-48b9-b992-56789b0dfe7e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_57506ad0-5cab-4cb2-a0a3-18d9aa8adcb1" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_9b7ea47a-64f8-48b9-b992-56789b0dfe7e" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_57506ad0-5cab-4cb2-a0a3-18d9aa8adcb1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConvertibleDebtMember_dcc7dab3-3a74-4d8b-a211-0440ca99a4ee" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ConvertibleDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_57506ad0-5cab-4cb2-a0a3-18d9aa8adcb1" xlink:to="loc_us-gaap_ConvertibleDebtMember_dcc7dab3-3a74-4d8b-a211-0440ca99a4ee" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pwp.com/role/CommitmentsandContingenciesAdditionalInformationDetails" xlink:type="simple" xlink:href="pwp-20221231.xsd#CommitmentsandContingenciesAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://pwp.com/role/CommitmentsandContingenciesAdditionalInformationDetails" xlink:type="extended" id="i276891a595e747d4b4d442c14af9bb7e_CommitmentsandContingenciesAdditionalInformationDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesLineItems_835c235a-1482-473f-81be-fb223d717bed" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LossContingenciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyEstimateOfPossibleLoss_a10a16dd-528f-4b73-843f-07c0d1baea14" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LossContingencyEstimateOfPossibleLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_835c235a-1482-473f-81be-fb223d717bed" xlink:to="loc_us-gaap_LossContingencyEstimateOfPossibleLoss_a10a16dd-528f-4b73-843f-07c0d1baea14" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtDefaultLongtermDebtAmount_e0b918e9-2c39-4202-bd73-695762fe73a2" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtDefaultLongtermDebtAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_835c235a-1482-473f-81be-fb223d717bed" xlink:to="loc_us-gaap_DebtDefaultLongtermDebtAmount_e0b918e9-2c39-4202-bd73-695762fe73a2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_LossContingencyPendingPlaintiffsClaimsNumber_320806bf-104e-429b-aac9-7fae06b4697b" xlink:href="pwp-20221231.xsd#pwp_LossContingencyPendingPlaintiffsClaimsNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_835c235a-1482-473f-81be-fb223d717bed" xlink:to="loc_pwp_LossContingencyPendingPlaintiffsClaimsNumber_320806bf-104e-429b-aac9-7fae06b4697b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_LossContingencyPendingCounterclaimsNumber_66192cba-b274-4da2-bb8f-e8313a962010" xlink:href="pwp-20221231.xsd#pwp_LossContingencyPendingCounterclaimsNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_835c235a-1482-473f-81be-fb223d717bed" xlink:to="loc_pwp_LossContingencyPendingCounterclaimsNumber_66192cba-b274-4da2-bb8f-e8313a962010" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyDamagesSoughtValue_523b5471-c346-4931-8db9-b7d78f610576" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LossContingencyDamagesSoughtValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_835c235a-1482-473f-81be-fb223d717bed" xlink:to="loc_us-gaap_LossContingencyDamagesSoughtValue_523b5471-c346-4931-8db9-b7d78f610576" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_LossContingencyPendingDefendantsClaimsNumber_8717ce13-53c7-4c20-a744-9f5a73585519" xlink:href="pwp-20221231.xsd#pwp_LossContingencyPendingDefendantsClaimsNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_835c235a-1482-473f-81be-fb223d717bed" xlink:to="loc_pwp_LossContingencyPendingDefendantsClaimsNumber_8717ce13-53c7-4c20-a744-9f5a73585519" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationSettlementExpense_486393b1-75a4-4645-99ec-2f5df72c871d" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LitigationSettlementExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_835c235a-1482-473f-81be-fb223d717bed" xlink:to="loc_us-gaap_LitigationSettlementExpense_486393b1-75a4-4645-99ec-2f5df72c871d" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesTable_05613d85-3686-4fce-9eb7-05157e0c8ffd" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LossContingenciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_835c235a-1482-473f-81be-fb223d717bed" xlink:to="loc_us-gaap_LossContingenciesTable_05613d85-3686-4fce-9eb7-05157e0c8ffd" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_ddf1cdba-cf91-4909-982f-d73bbb473e71" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_05613d85-3686-4fce-9eb7-05157e0c8ffd" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_ddf1cdba-cf91-4909-982f-d73bbb473e71" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_ddf1cdba-cf91-4909-982f-d73bbb473e71_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_ddf1cdba-cf91-4909-982f-d73bbb473e71" xlink:to="loc_us-gaap_LossContingencyNatureDomain_ddf1cdba-cf91-4909-982f-d73bbb473e71_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_52946945-6afc-4601-bdc0-35c2da6cf8fa" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_ddf1cdba-cf91-4909-982f-d73bbb473e71" xlink:to="loc_us-gaap_LossContingencyNatureDomain_52946945-6afc-4601-bdc0-35c2da6cf8fa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GuaranteeOfIndebtednessOfOthersMember_aefc4ba1-587f-4b07-9cf9-43805691996f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_GuaranteeOfIndebtednessOfOthersMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_52946945-6afc-4601-bdc0-35c2da6cf8fa" xlink:to="loc_us-gaap_GuaranteeOfIndebtednessOfOthersMember_aefc4ba1-587f-4b07-9cf9-43805691996f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndemnificationGuaranteeMember_ae18cae7-4dcc-42cb-ad82-48c7b14e6883" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IndemnificationGuaranteeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_52946945-6afc-4601-bdc0-35c2da6cf8fa" xlink:to="loc_us-gaap_IndemnificationGuaranteeMember_ae18cae7-4dcc-42cb-ad82-48c7b14e6883" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusAxis_d034b041-4d93-4a2d-a0e2-60c5527d7c69" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LitigationStatusAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_05613d85-3686-4fce-9eb7-05157e0c8ffd" xlink:to="loc_us-gaap_LitigationStatusAxis_d034b041-4d93-4a2d-a0e2-60c5527d7c69" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusDomain_d034b041-4d93-4a2d-a0e2-60c5527d7c69_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LitigationStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LitigationStatusAxis_d034b041-4d93-4a2d-a0e2-60c5527d7c69" xlink:to="loc_us-gaap_LitigationStatusDomain_d034b041-4d93-4a2d-a0e2-60c5527d7c69_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusDomain_d4c9ebfd-7744-4412-a006-127f32903f33" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LitigationStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LitigationStatusAxis_d034b041-4d93-4a2d-a0e2-60c5527d7c69" xlink:to="loc_us-gaap_LitigationStatusDomain_d4c9ebfd-7744-4412-a006-127f32903f33" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PendingLitigationMember_a65feb40-2595-4878-99c3-d2c824605254" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PendingLitigationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LitigationStatusDomain_d4c9ebfd-7744-4412-a006-127f32903f33" xlink:to="loc_us-gaap_PendingLitigationMember_a65feb40-2595-4878-99c3-d2c824605254" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_PendingDismissalMember_b13879f9-0db8-42b8-a50b-6eb47c2bf3db" xlink:href="pwp-20221231.xsd#pwp_PendingDismissalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LitigationStatusDomain_d4c9ebfd-7744-4412-a006-127f32903f33" xlink:to="loc_pwp_PendingDismissalMember_b13879f9-0db8-42b8-a50b-6eb47c2bf3db" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_PendingLitigationAfterPendingDismissalMember_037d6410-081c-45fe-8bca-05afd8bb6df2" xlink:href="pwp-20221231.xsd#pwp_PendingLitigationAfterPendingDismissalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LitigationStatusDomain_d4c9ebfd-7744-4412-a006-127f32903f33" xlink:to="loc_pwp_PendingLitigationAfterPendingDismissalMember_037d6410-081c-45fe-8bca-05afd8bb6df2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_MotionForLeaveToRenewMember_a24b9a91-c7a8-4c1d-9f0d-bb34a38b0cac" xlink:href="pwp-20221231.xsd#pwp_MotionForLeaveToRenewMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LitigationStatusDomain_d4c9ebfd-7744-4412-a006-127f32903f33" xlink:to="loc_pwp_MotionForLeaveToRenewMember_a24b9a91-c7a8-4c1d-9f0d-bb34a38b0cac" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_6ab0b955-480d-43f6-b7f0-fca868488e09" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_05613d85-3686-4fce-9eb7-05157e0c8ffd" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_6ab0b955-480d-43f6-b7f0-fca868488e09" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_6ab0b955-480d-43f6-b7f0-fca868488e09_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_6ab0b955-480d-43f6-b7f0-fca868488e09" xlink:to="loc_us-gaap_RelatedPartyDomain_6ab0b955-480d-43f6-b7f0-fca868488e09_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_cb651633-343d-4e25-9bb7-9a37fff1d21b" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_6ab0b955-480d-43f6-b7f0-fca868488e09" xlink:to="loc_us-gaap_RelatedPartyDomain_cb651633-343d-4e25-9bb7-9a37fff1d21b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_PartnersMember_860471dc-d547-4e22-a584-61021f01173e" xlink:href="pwp-20221231.xsd#pwp_PartnersMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_cb651633-343d-4e25-9bb7-9a37fff1d21b" xlink:to="loc_pwp_PartnersMember_860471dc-d547-4e22-a584-61021f01173e" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pwp.com/role/BusinessInformationAdditionalInformationDetails" xlink:type="simple" xlink:href="pwp-20221231.xsd#BusinessInformationAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://pwp.com/role/BusinessInformationAdditionalInformationDetails" xlink:type="extended" id="i4c32df7ae02a4ac891e52b22cce141ee_BusinessInformationAdditionalInformationDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_93f2da26-e472-47f8-adf9-f65c008ab4cf" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfOperatingSegments_33c20d95-3011-4e65-9f41-f09e56326d85" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NumberOfOperatingSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_93f2da26-e472-47f8-adf9-f65c008ab4cf" xlink:to="loc_us-gaap_NumberOfOperatingSegments_33c20d95-3011-4e65-9f41-f09e56326d85" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfReportableSegments_5d0535b9-dfde-4b02-98f6-95d6f4eacde7" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NumberOfReportableSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_93f2da26-e472-47f8-adf9-f65c008ab4cf" xlink:to="loc_us-gaap_NumberOfReportableSegments_5d0535b9-dfde-4b02-98f6-95d6f4eacde7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_NumberOfClientsOverTenPercentBenchmark_719216c2-fe93-4d66-8b36-e917f379de78" xlink:href="pwp-20221231.xsd#pwp_NumberOfClientsOverTenPercentBenchmark"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_93f2da26-e472-47f8-adf9-f65c008ab4cf" xlink:to="loc_pwp_NumberOfClientsOverTenPercentBenchmark_719216c2-fe93-4d66-8b36-e917f379de78" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_ef44b153-6b17-4e2b-865c-6ea4a7d6dd81" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_93f2da26-e472-47f8-adf9-f65c008ab4cf" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_ef44b153-6b17-4e2b-865c-6ea4a7d6dd81" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_90b83813-4123-4f2d-8c61-43435d82e7c0" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_ef44b153-6b17-4e2b-865c-6ea4a7d6dd81" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_90b83813-4123-4f2d-8c61-43435d82e7c0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_90b83813-4123-4f2d-8c61-43435d82e7c0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_90b83813-4123-4f2d-8c61-43435d82e7c0" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_90b83813-4123-4f2d-8c61-43435d82e7c0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_bd8408ac-e6cd-4dc4-a9ef-6f361471641a" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_90b83813-4123-4f2d-8c61-43435d82e7c0" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_bd8408ac-e6cd-4dc4-a9ef-6f361471641a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SalesRevenueNetMember_1dac8d14-ffda-4e3e-95d5-45651497ac85" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SalesRevenueNetMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_bd8408ac-e6cd-4dc4-a9ef-6f361471641a" xlink:to="loc_us-gaap_SalesRevenueNetMember_1dac8d14-ffda-4e3e-95d5-45651497ac85" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_064353c4-1ed3-493b-bc58-18a8edfcd99c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ConcentrationRiskByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_ef44b153-6b17-4e2b-865c-6ea4a7d6dd81" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_064353c4-1ed3-493b-bc58-18a8edfcd99c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_064353c4-1ed3-493b-bc58-18a8edfcd99c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_064353c4-1ed3-493b-bc58-18a8edfcd99c" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_064353c4-1ed3-493b-bc58-18a8edfcd99c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_9160f2a9-39e4-41ea-b00c-aea7662b235f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_064353c4-1ed3-493b-bc58-18a8edfcd99c" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_9160f2a9-39e4-41ea-b00c-aea7662b235f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerConcentrationRiskMember_7013b7a2-b59d-408e-8ea4-20cf31a555cb" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CustomerConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_9160f2a9-39e4-41ea-b00c-aea7662b235f" xlink:to="loc_us-gaap_CustomerConcentrationRiskMember_7013b7a2-b59d-408e-8ea4-20cf31a555cb" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pwp.com/role/BusinessInformationScheduleofGeographicalDistributionofRevenuesandAssetsDetails" xlink:type="simple" xlink:href="pwp-20221231.xsd#BusinessInformationScheduleofGeographicalDistributionofRevenuesandAssetsDetails"/>
  <link:definitionLink xlink:role="http://pwp.com/role/BusinessInformationScheduleofGeographicalDistributionofRevenuesandAssetsDetails" xlink:type="extended" id="i1d9bb0931fa34e2ab33adca7d21a4b5b_BusinessInformationScheduleofGeographicalDistributionofRevenuesandAssetsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_75ce589e-37b1-454c-a351-6a6081e42a33" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_438ea77a-528f-4083-9418-da732c59fbbb" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_75ce589e-37b1-454c-a351-6a6081e42a33" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_438ea77a-528f-4083-9418-da732c59fbbb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_8b7abfec-1084-459d-a8e3-71b25a0bf209" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_75ce589e-37b1-454c-a351-6a6081e42a33" xlink:to="loc_us-gaap_Assets_8b7abfec-1084-459d-a8e3-71b25a0bf209" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_ab3f1641-9463-48a0-9aa8-a9d1538036d0" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_75ce589e-37b1-454c-a351-6a6081e42a33" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_ab3f1641-9463-48a0-9aa8-a9d1538036d0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_0f78adfe-630c-46bd-bef5-0fb39297623a" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_ab3f1641-9463-48a0-9aa8-a9d1538036d0" xlink:to="loc_srt_StatementGeographicalAxis_0f78adfe-630c-46bd-bef5-0fb39297623a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_0f78adfe-630c-46bd-bef5-0fb39297623a_default" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_0f78adfe-630c-46bd-bef5-0fb39297623a" xlink:to="loc_srt_SegmentGeographicalDomain_0f78adfe-630c-46bd-bef5-0fb39297623a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_92424f11-ff2e-40d9-a742-56a780b4cad9" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_0f78adfe-630c-46bd-bef5-0fb39297623a" xlink:to="loc_srt_SegmentGeographicalDomain_92424f11-ff2e-40d9-a742-56a780b4cad9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_d931c103-767e-43ff-b391-58075fc93de3" xlink:href="https://xbrl.sec.gov/country/2022/country-2022.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_92424f11-ff2e-40d9-a742-56a780b4cad9" xlink:to="loc_country_US_d931c103-767e-43ff-b391-58075fc93de3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonUsMember_81c07f8d-acab-4e2b-b519-81d2715da0f3" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NonUsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_92424f11-ff2e-40d9-a742-56a780b4cad9" xlink:to="loc_us-gaap_NonUsMember_81c07f8d-acab-4e2b-b519-81d2715da0f3" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://pwp.com/role/SubsequentEventsAdditionalInformationDetails" xlink:type="simple" xlink:href="pwp-20221231.xsd#SubsequentEventsAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://pwp.com/role/SubsequentEventsAdditionalInformationDetails" xlink:type="extended" id="if8e0da80699349f8b28fcb306d2345bc_SubsequentEventsAdditionalInformationDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventLineItems_3e924a5f-ea45-4762-8faa-5f29026ff463" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SubsequentEventLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_7aadf769-9ee0-4e54-bc8a-209031646523" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_3e924a5f-ea45-4762-8faa-5f29026ff463" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_7aadf769-9ee0-4e54-bc8a-209031646523" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_3ad8fe2d-5ada-4876-9160-02b90460e621" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_3e924a5f-ea45-4762-8faa-5f29026ff463" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_3ad8fe2d-5ada-4876-9160-02b90460e621" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockDividendsPerShareDeclared_dfa0a687-93d0-48fb-9530-5b6e33e65997" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonStockDividendsPerShareDeclared"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_3e924a5f-ea45-4762-8faa-5f29026ff463" xlink:to="loc_us-gaap_CommonStockDividendsPerShareDeclared_dfa0a687-93d0-48fb-9530-5b6e33e65997" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_DividendsAndDistributionsRate_9ebc7996-e2b3-4de2-803f-251af2f1f790" xlink:href="pwp-20221231.xsd#pwp_DividendsAndDistributionsRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_3e924a5f-ea45-4762-8faa-5f29026ff463" xlink:to="loc_pwp_DividendsAndDistributionsRate_9ebc7996-e2b3-4de2-803f-251af2f1f790" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchaseProgramAuthorizedAmount1_3dd93571-70d4-4a88-b87e-35bbd969aeb3" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockRepurchaseProgramAuthorizedAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_3e924a5f-ea45-4762-8faa-5f29026ff463" xlink:to="loc_us-gaap_StockRepurchaseProgramAuthorizedAmount1_3dd93571-70d4-4a88-b87e-35bbd969aeb3" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTable_0ec46cc4-f610-4dfb-bc37-510b7ab1ba9f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SubsequentEventTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SubsequentEventLineItems_3e924a5f-ea45-4762-8faa-5f29026ff463" xlink:to="loc_us-gaap_SubsequentEventTable_0ec46cc4-f610-4dfb-bc37-510b7ab1ba9f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_90181c1c-4031-40f7-bf22-91cc94fe6360" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_0ec46cc4-f610-4dfb-bc37-510b7ab1ba9f" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_90181c1c-4031-40f7-bf22-91cc94fe6360" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_90181c1c-4031-40f7-bf22-91cc94fe6360_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_90181c1c-4031-40f7-bf22-91cc94fe6360" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_90181c1c-4031-40f7-bf22-91cc94fe6360_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_5015e56b-6c7a-4d4a-a22d-db134fa27ca8" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_90181c1c-4031-40f7-bf22-91cc94fe6360" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_5015e56b-6c7a-4d4a-a22d-db134fa27ca8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_ae599684-28dc-4c67-aa57-69db113f001c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_5015e56b-6c7a-4d4a-a22d-db134fa27ca8" xlink:to="loc_us-gaap_SubsequentEventMember_ae599684-28dc-4c67-aa57-69db113f001c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_bb430c3b-62a5-4e1a-975b-aa15384d4594" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_0ec46cc4-f610-4dfb-bc37-510b7ab1ba9f" xlink:to="loc_us-gaap_PlanNameAxis_bb430c3b-62a5-4e1a-975b-aa15384d4594" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_bb430c3b-62a5-4e1a-975b-aa15384d4594_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_bb430c3b-62a5-4e1a-975b-aa15384d4594" xlink:to="loc_us-gaap_PlanNameDomain_bb430c3b-62a5-4e1a-975b-aa15384d4594_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_84d49dcb-d2a1-4a3b-b228-040a38675c1f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_bb430c3b-62a5-4e1a-975b-aa15384d4594" xlink:to="loc_us-gaap_PlanNameDomain_84d49dcb-d2a1-4a3b-b228-040a38675c1f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_PerellaWeinbergPartners2021OmnibusIncentivePlanMember_12adfa52-24c5-493a-b044-e5c34a76da27" xlink:href="pwp-20221231.xsd#pwp_PerellaWeinbergPartners2021OmnibusIncentivePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_84d49dcb-d2a1-4a3b-b228-040a38675c1f" xlink:to="loc_pwp_PerellaWeinbergPartners2021OmnibusIncentivePlanMember_12adfa52-24c5-493a-b044-e5c34a76da27" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_bc5b4838-4375-4327-9d2f-9b44b6ac7fa6" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_0ec46cc4-f610-4dfb-bc37-510b7ab1ba9f" xlink:to="loc_us-gaap_AwardTypeAxis_bc5b4838-4375-4327-9d2f-9b44b6ac7fa6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_bc5b4838-4375-4327-9d2f-9b44b6ac7fa6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_bc5b4838-4375-4327-9d2f-9b44b6ac7fa6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_bc5b4838-4375-4327-9d2f-9b44b6ac7fa6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_adc91be4-e821-4b15-aaed-2f8b85155a06" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_bc5b4838-4375-4327-9d2f-9b44b6ac7fa6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_adc91be4-e821-4b15-aaed-2f8b85155a06" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_5620c12c-0690-4875-806a-2b0cfda9f1d7" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_adc91be4-e821-4b15-aaed-2f8b85155a06" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_5620c12c-0690-4875-806a-2b0cfda9f1d7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_TransactionPoolPsusMember_9af291b8-8664-4025-bc33-5044472d40cb" xlink:href="pwp-20221231.xsd#pwp_TransactionPoolPsusMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_adc91be4-e821-4b15-aaed-2f8b85155a06" xlink:to="loc_pwp_TransactionPoolPsusMember_9af291b8-8664-4025-bc33-5044472d40cb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pwp_GeneralPSUsMember_a93997de-d017-45a5-8723-9e39847d9389" xlink:href="pwp-20221231.xsd#pwp_GeneralPSUsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_adc91be4-e821-4b15-aaed-2f8b85155a06" xlink:to="loc_pwp_GeneralPSUsMember_a93997de-d017-45a5-8723-9e39847d9389" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_910ba3bb-3c92-4d52-a238-651bfbe4c94f" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_0ec46cc4-f610-4dfb-bc37-510b7ab1ba9f" xlink:to="loc_us-gaap_StatementClassOfStockAxis_910ba3bb-3c92-4d52-a238-651bfbe4c94f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_910ba3bb-3c92-4d52-a238-651bfbe4c94f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_910ba3bb-3c92-4d52-a238-651bfbe4c94f" xlink:to="loc_us-gaap_ClassOfStockDomain_910ba3bb-3c92-4d52-a238-651bfbe4c94f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_92217729-babe-4f7d-8ac9-38a17de6e827" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_910ba3bb-3c92-4d52-a238-651bfbe4c94f" xlink:to="loc_us-gaap_ClassOfStockDomain_92217729-babe-4f7d-8ac9-38a17de6e827" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_42291cf2-2a0c-4509-9f4b-b30f8fe73aa0" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_92217729-babe-4f7d-8ac9-38a17de6e827" xlink:to="loc_us-gaap_CommonClassAMember_42291cf2-2a0c-4509-9f4b-b30f8fe73aa0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassBMember_d8cdc09a-6f60-4878-a249-1c6525dfa78c" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonClassBMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_92217729-babe-4f7d-8ac9-38a17de6e827" xlink:to="loc_us-gaap_CommonClassBMember_d8cdc09a-6f60-4878-a249-1c6525dfa78c" xlink:type="arc" order="1"/>
  </link:definitionLink>
</link:linkbase>
