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

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:019eb887-3ead-7536-9d75-5fefb974d9a4,g:ec7a4da9-b0db-4b9d-815e-f884bb2f1288-->
<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://carlylesecuredlending.com/role/Cover" xlink:type="simple" xlink:href="csl-20260715.xsd#Cover"/>
  <link:definitionLink xlink:role="http://carlylesecuredlending.com/role/Cover" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019eb887-3ead-7b32-ae68-bd9ed91a2233" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityListingsTable_019eb887-3ead-7c0d-b1af-cff60014f842" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityListingsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019eb887-3ead-7b32-ae68-bd9ed91a2233" xlink:to="loc_dei_EntityListingsTable_019eb887-3ead-7c0d-b1af-cff60014f842" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019eb887-3ead-7cc5-b487-22dc3cdd9b3e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_dei_EntityListingsTable_019eb887-3ead-7c0d-b1af-cff60014f842" xlink:to="loc_us-gaap_DebtInstrumentAxis_019eb887-3ead-7cc5-b487-22dc3cdd9b3e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019eb887-3ead-7cc5-b487-22dc3cdd9b3e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019eb887-3ead-7cc5-b487-22dc3cdd9b3e" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019eb887-3ead-7cc5-b487-22dc3cdd9b3e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019eb887-3ead-7012-87c3-279623fc7692" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019eb887-3ead-7cc5-b487-22dc3cdd9b3e" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019eb887-3ead-7012-87c3-279623fc7692" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_csl_A820NotesDue2028Member_019eb887-3ead-7ee7-9644-5966d9bd917d" xlink:href="csl-20260715.xsd#csl_A820NotesDue2028Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019eb887-3ead-7012-87c3-279623fc7692" xlink:to="loc_csl_A820NotesDue2028Member_019eb887-3ead-7ee7-9644-5966d9bd917d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentType_019eb887-3ead-70f9-9074-b8c5cd4b1617" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentType"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019eb887-3ead-7b32-ae68-bd9ed91a2233" xlink:to="loc_dei_DocumentType_019eb887-3ead-70f9-9074-b8c5cd4b1617" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_AmendmentFlag_019eb887-3ead-7e27-9116-b4c14a9a4ac8" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_AmendmentFlag"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019eb887-3ead-7b32-ae68-bd9ed91a2233" xlink:to="loc_dei_AmendmentFlag_019eb887-3ead-7e27-9116-b4c14a9a4ac8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentPeriodEndDate_019eb887-3ead-7476-9e70-4e3edd1b3eb3" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentPeriodEndDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019eb887-3ead-7b32-ae68-bd9ed91a2233" xlink:to="loc_dei_DocumentPeriodEndDate_019eb887-3ead-7476-9e70-4e3edd1b3eb3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityRegistrantName_019eb887-3ead-707c-a02e-fdfd5a518faf" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityRegistrantName"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019eb887-3ead-7b32-ae68-bd9ed91a2233" xlink:to="loc_dei_EntityRegistrantName_019eb887-3ead-707c-a02e-fdfd5a518faf" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCentralIndexKey_019eb887-3ead-7f67-a968-66611c9d23e6" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityCentralIndexKey"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019eb887-3ead-7b32-ae68-bd9ed91a2233" xlink:to="loc_dei_EntityCentralIndexKey_019eb887-3ead-7f67-a968-66611c9d23e6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityIncorporationStateCountryCode_019eb887-3ead-7687-932b-cf4e0af1b775" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityIncorporationStateCountryCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019eb887-3ead-7b32-ae68-bd9ed91a2233" xlink:to="loc_dei_EntityIncorporationStateCountryCode_019eb887-3ead-7687-932b-cf4e0af1b775" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityFileNumber_019eb887-3ead-7885-b817-e0bfda8c8de9" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityFileNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019eb887-3ead-7b32-ae68-bd9ed91a2233" xlink:to="loc_dei_EntityFileNumber_019eb887-3ead-7885-b817-e0bfda8c8de9" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityTaxIdentificationNumber_019eb887-3ead-7388-9f5d-8fd8b4de434a" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityTaxIdentificationNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019eb887-3ead-7b32-ae68-bd9ed91a2233" xlink:to="loc_dei_EntityTaxIdentificationNumber_019eb887-3ead-7388-9f5d-8fd8b4de434a" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressAddressLine1_019eb887-3ead-7d87-8f81-aa41f9dd08c0" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressAddressLine1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019eb887-3ead-7b32-ae68-bd9ed91a2233" xlink:to="loc_dei_EntityAddressAddressLine1_019eb887-3ead-7d87-8f81-aa41f9dd08c0" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressCityOrTown_019eb887-3ead-720d-b5bd-ea334decc735" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressCityOrTown"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019eb887-3ead-7b32-ae68-bd9ed91a2233" xlink:to="loc_dei_EntityAddressCityOrTown_019eb887-3ead-720d-b5bd-ea334decc735" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressStateOrProvince_019eb887-3ead-72b7-86c2-08be25f45791" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressStateOrProvince"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019eb887-3ead-7b32-ae68-bd9ed91a2233" xlink:to="loc_dei_EntityAddressStateOrProvince_019eb887-3ead-72b7-86c2-08be25f45791" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressPostalZipCode_019eb887-3ead-7565-92dd-b6a4ce86167a" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressPostalZipCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019eb887-3ead-7b32-ae68-bd9ed91a2233" xlink:to="loc_dei_EntityAddressPostalZipCode_019eb887-3ead-7565-92dd-b6a4ce86167a" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_CityAreaCode_019eb887-3ead-7fe0-99ea-2b4340f6d90f" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_CityAreaCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019eb887-3ead-7b32-ae68-bd9ed91a2233" xlink:to="loc_dei_CityAreaCode_019eb887-3ead-7fe0-99ea-2b4340f6d90f" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LocalPhoneNumber_019eb887-3ead-746f-9f5b-4923fc844c6e" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_LocalPhoneNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019eb887-3ead-7b32-ae68-bd9ed91a2233" xlink:to="loc_dei_LocalPhoneNumber_019eb887-3ead-746f-9f5b-4923fc844c6e" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_WrittenCommunications_019eb887-3ead-7d76-b9dc-8b600d207fd5" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_WrittenCommunications"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019eb887-3ead-7b32-ae68-bd9ed91a2233" xlink:to="loc_dei_WrittenCommunications_019eb887-3ead-7d76-b9dc-8b600d207fd5" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_SolicitingMaterial_019eb887-3ead-750a-ada7-5d5b722e23c9" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_SolicitingMaterial"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019eb887-3ead-7b32-ae68-bd9ed91a2233" xlink:to="loc_dei_SolicitingMaterial_019eb887-3ead-750a-ada7-5d5b722e23c9" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_PreCommencementTenderOffer_019eb887-3ead-7fff-9d1e-3dbd92dec3f3" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_PreCommencementTenderOffer"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019eb887-3ead-7b32-ae68-bd9ed91a2233" xlink:to="loc_dei_PreCommencementTenderOffer_019eb887-3ead-7fff-9d1e-3dbd92dec3f3" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_PreCommencementIssuerTenderOffer_019eb887-3ead-7d18-b712-83aae0889aa0" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_PreCommencementIssuerTenderOffer"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019eb887-3ead-7b32-ae68-bd9ed91a2233" xlink:to="loc_dei_PreCommencementIssuerTenderOffer_019eb887-3ead-7d18-b712-83aae0889aa0" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_Security12bTitle_019eb887-3ead-7419-8079-3cb90933bd71" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_Security12bTitle"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019eb887-3ead-7b32-ae68-bd9ed91a2233" xlink:to="loc_dei_Security12bTitle_019eb887-3ead-7419-8079-3cb90933bd71" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_TradingSymbol_019eb887-3ead-7a63-a5d1-c55b17a15c31" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_TradingSymbol"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019eb887-3ead-7b32-ae68-bd9ed91a2233" xlink:to="loc_dei_TradingSymbol_019eb887-3ead-7a63-a5d1-c55b17a15c31" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_SecurityExchangeName_019eb887-3ead-7ba5-a18d-10ea6280d3ea" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_SecurityExchangeName"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019eb887-3ead-7b32-ae68-bd9ed91a2233" xlink:to="loc_dei_SecurityExchangeName_019eb887-3ead-7ba5-a18d-10ea6280d3ea" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityEmergingGrowthCompany_019eb887-3ead-7321-a988-1ceaf655ba72" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityEmergingGrowthCompany"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019eb887-3ead-7b32-ae68-bd9ed91a2233" xlink:to="loc_dei_EntityEmergingGrowthCompany_019eb887-3ead-7321-a988-1ceaf655ba72" xlink:type="arc" order="21"/>
  </link:definitionLink>
</link:linkbase>
