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

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:019f1eba-02d6-7770-a7c8-21268a6623cb,g:47d4092f-03ff-45e4-9296-f8aadb7cfd68-->
<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" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:roleRef roleURI="http://fastly.com/role/CoverPage" xlink:type="simple" xlink:href="fsly-20260805.xsd#CoverPage"/>
  <link:presentationLink xlink:role="http://fastly.com/role/CoverPage" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_dei_CoverAbstract_019f1eba-02d6-73e2-adbe-22ef3dcdf003" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_CoverAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentType_019f1eba-02d6-7846-98b8-d39175e893f5" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_DocumentType"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_019f1eba-02d6-73e2-adbe-22ef3dcdf003" xlink:to="loc_dei_DocumentType_019f1eba-02d6-7846-98b8-d39175e893f5" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentPeriodEndDate_019f1eba-02d6-78fc-82a4-89bb6c49bb7a" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_DocumentPeriodEndDate"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_019f1eba-02d6-73e2-adbe-22ef3dcdf003" xlink:to="loc_dei_DocumentPeriodEndDate_019f1eba-02d6-78fc-82a4-89bb6c49bb7a" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityRegistrantName_019f1eba-02d6-74a1-9ed2-2a2376bf6263" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityRegistrantName"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_019f1eba-02d6-73e2-adbe-22ef3dcdf003" xlink:to="loc_dei_EntityRegistrantName_019f1eba-02d6-74a1-9ed2-2a2376bf6263" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityIncorporationStateCountryCode_019f1eba-02d6-7c25-920c-6fd5a1c182a3" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityIncorporationStateCountryCode"/>
    <link:presentationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_019f1eba-02d6-73e2-adbe-22ef3dcdf003" xlink:to="loc_dei_EntityIncorporationStateCountryCode_019f1eba-02d6-7c25-920c-6fd5a1c182a3" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityFileNumber_019f1eba-02d6-7a26-90c9-04b5ad17becf" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityFileNumber"/>
    <link:presentationArc order="5" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_019f1eba-02d6-73e2-adbe-22ef3dcdf003" xlink:to="loc_dei_EntityFileNumber_019f1eba-02d6-7a26-90c9-04b5ad17becf" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityTaxIdentificationNumber_019f1eba-02d6-7532-90a7-33fa27346a0e" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityTaxIdentificationNumber"/>
    <link:presentationArc order="6" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_019f1eba-02d6-73e2-adbe-22ef3dcdf003" xlink:to="loc_dei_EntityTaxIdentificationNumber_019f1eba-02d6-7532-90a7-33fa27346a0e" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressAddressLine1_019f1eba-02d6-7af6-b406-46968c15f1f8" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityAddressAddressLine1"/>
    <link:presentationArc order="7" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_019f1eba-02d6-73e2-adbe-22ef3dcdf003" xlink:to="loc_dei_EntityAddressAddressLine1_019f1eba-02d6-7af6-b406-46968c15f1f8" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressCityOrTown_019f1eba-02d6-7ad0-9a77-635db8eccd6b" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityAddressCityOrTown"/>
    <link:presentationArc order="8" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_019f1eba-02d6-73e2-adbe-22ef3dcdf003" xlink:to="loc_dei_EntityAddressCityOrTown_019f1eba-02d6-7ad0-9a77-635db8eccd6b" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressStateOrProvince_019f1eba-02d6-7882-8501-b82137ac7fe8" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityAddressStateOrProvince"/>
    <link:presentationArc order="9" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_019f1eba-02d6-73e2-adbe-22ef3dcdf003" xlink:to="loc_dei_EntityAddressStateOrProvince_019f1eba-02d6-7882-8501-b82137ac7fe8" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressPostalZipCode_019f1eba-02d6-7ede-ac43-5bbde06cf63b" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityAddressPostalZipCode"/>
    <link:presentationArc order="10" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_019f1eba-02d6-73e2-adbe-22ef3dcdf003" xlink:to="loc_dei_EntityAddressPostalZipCode_019f1eba-02d6-7ede-ac43-5bbde06cf63b" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_CityAreaCode_019f1eba-02d6-7054-8a6c-8f1a25844d82" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_CityAreaCode"/>
    <link:presentationArc order="11" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_019f1eba-02d6-73e2-adbe-22ef3dcdf003" xlink:to="loc_dei_CityAreaCode_019f1eba-02d6-7054-8a6c-8f1a25844d82" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LocalPhoneNumber_019f1eba-02d6-7108-8f8d-bd5b36c0f068" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_LocalPhoneNumber"/>
    <link:presentationArc order="12" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_019f1eba-02d6-73e2-adbe-22ef3dcdf003" xlink:to="loc_dei_LocalPhoneNumber_019f1eba-02d6-7108-8f8d-bd5b36c0f068" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_WrittenCommunications_019f1eba-02d6-711e-a305-cea923813c6b" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_WrittenCommunications"/>
    <link:presentationArc order="13" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_019f1eba-02d6-73e2-adbe-22ef3dcdf003" xlink:to="loc_dei_WrittenCommunications_019f1eba-02d6-711e-a305-cea923813c6b" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_SolicitingMaterial_019f1eba-02d6-79f3-8a2b-fc96b487ca08" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_SolicitingMaterial"/>
    <link:presentationArc order="14" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_019f1eba-02d6-73e2-adbe-22ef3dcdf003" xlink:to="loc_dei_SolicitingMaterial_019f1eba-02d6-79f3-8a2b-fc96b487ca08" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_PreCommencementTenderOffer_019f1eba-02d6-7d0e-a74c-009b0ca99422" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_PreCommencementTenderOffer"/>
    <link:presentationArc order="15" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_019f1eba-02d6-73e2-adbe-22ef3dcdf003" xlink:to="loc_dei_PreCommencementTenderOffer_019f1eba-02d6-7d0e-a74c-009b0ca99422" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_PreCommencementIssuerTenderOffer_019f1eba-02d6-764a-a4b8-264ccf675e11" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_PreCommencementIssuerTenderOffer"/>
    <link:presentationArc order="16" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_019f1eba-02d6-73e2-adbe-22ef3dcdf003" xlink:to="loc_dei_PreCommencementIssuerTenderOffer_019f1eba-02d6-764a-a4b8-264ccf675e11" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_Security12bTitle_019f1eba-02d6-781b-a03d-1f8af43ee32d" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_Security12bTitle"/>
    <link:presentationArc order="17" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_019f1eba-02d6-73e2-adbe-22ef3dcdf003" xlink:to="loc_dei_Security12bTitle_019f1eba-02d6-781b-a03d-1f8af43ee32d" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_TradingSymbol_019f1eba-02d6-75d4-99d7-0f126ed1292d" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_TradingSymbol"/>
    <link:presentationArc order="18" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_019f1eba-02d6-73e2-adbe-22ef3dcdf003" xlink:to="loc_dei_TradingSymbol_019f1eba-02d6-75d4-99d7-0f126ed1292d" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_SecurityExchangeName_019f1eba-02d6-7515-8fee-2ce60c1d26cd" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_SecurityExchangeName"/>
    <link:presentationArc order="19" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_019f1eba-02d6-73e2-adbe-22ef3dcdf003" xlink:to="loc_dei_SecurityExchangeName_019f1eba-02d6-7515-8fee-2ce60c1d26cd" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityEmergingGrowthCompany_019f1eba-02d6-7e72-a979-339422b481bd" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityEmergingGrowthCompany"/>
    <link:presentationArc order="20" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_019f1eba-02d6-73e2-adbe-22ef3dcdf003" xlink:to="loc_dei_EntityEmergingGrowthCompany_019f1eba-02d6-7e72-a979-339422b481bd" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCentralIndexKey_019f1eba-02d6-70a3-b6e5-0a3c882780aa" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityCentralIndexKey"/>
    <link:presentationArc order="21" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_019f1eba-02d6-73e2-adbe-22ef3dcdf003" xlink:to="loc_dei_EntityCentralIndexKey_019f1eba-02d6-70a3-b6e5-0a3c882780aa" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_AmendmentFlag_019f1eba-02d6-755e-bffd-4f0d49e74a49" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_AmendmentFlag"/>
    <link:presentationArc order="22" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_019f1eba-02d6-73e2-adbe-22ef3dcdf003" xlink:to="loc_dei_AmendmentFlag_019f1eba-02d6-755e-bffd-4f0d49e74a49" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
</link:linkbase>
