<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0206</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2020-12-08</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001792789</issuerCik>
        <issuerName>DoorDash Inc</issuerName>
        <issuerTradingSymbol>DASH</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001835490</rptOwnerCik>
            <rptOwnerName>SVF Fast (Cayman) Ltd</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O WALKERS CORP LTD 27 HOSPITAL ROAD</rptOwnerStreet1>
            <rptOwnerStreet2>CAYMAN CORPORATE CENTRE, GEORGETOWN</rptOwnerStreet2>
            <rptOwnerCity>GRAND CAYMAN</rptOwnerCity>
            <rptOwnerState>E9</rptOwnerState>
            <rptOwnerZipCode>KY1-9008</rptOwnerZipCode>
            <rptOwnerStateDescription>CAYMAN ISLANDS</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001731509</rptOwnerCik>
            <rptOwnerName>SB INVESTMENT ADVISERS (UK) LTD</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>69 GROSVENOR STREET MAYFAIR</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>LONDON</rptOwnerCity>
            <rptOwnerState>X0</rptOwnerState>
            <rptOwnerZipCode>W1K 3JP</rptOwnerZipCode>
            <rptOwnerStateDescription>UNITED KINGDOM</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001805808</rptOwnerCik>
            <rptOwnerName>SOFTBANK VISION FUND (AIV M2) L.P.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>251 LITTLE FALLS DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>WILMINGTON</rptOwnerCity>
            <rptOwnerState>DE</rptOwnerState>
            <rptOwnerZipCode>19808</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Series D Convertible Preferred Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F1"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                    <footnoteId id="F2"/>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>50845490</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Series F Convertible Preferred Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F5"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F5"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F5"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                    <footnoteId id="F2"/>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>4449370</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Series G Convertible Preferred Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F6"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F6"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F6"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                    <footnoteId id="F2"/>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>6589450</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Series H Convertible Preferred Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F7"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F7"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F7"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                    <footnoteId id="F2"/>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1089175</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Each share of Series D Convertible Preferred Stock shall automatically convert into Common Stock on a 1:1 basis immediately prior to the completion of the Issuer's initial public offering of Class A Common Stock and has no expiration date.</footnote>
        <footnote id="F2">Immediately prior to the completion of the Issuer's initial public offering of Class A Common Stock, each share of Common Stock shall be reclassified into one share of Class A Common Stock.</footnote>
        <footnote id="F3">These securities are held of record by SVF Fast (Cayman) Limited, which is a wholly owned subsidiary of SoftBank Vision Fund (AIV M2) L.P. SB Investment Advisers (UK) Limited has been appointed as alternative investment fund manager, or AIFM, of SoftBank Vision Fund (AIV M2) L.P., and is exclusively responsible for managing SoftBank Vision Fund (AIV M2) L.P. in accordance with the Alternative Investment Fund Managers Directive and is authorized and regulated by the UK Financial Conduct Authority accordingly. As AIFM of SoftBank Vision Fund (AIV M2) L.P., SB Investment Advisers (UK) Limited is exclusively responsible for making all decisions related to the acquisition, structuring, financing and disposal of SoftBank Vision Fund (AIV M2) L.P.'s investments.</footnote>
        <footnote id="F4">Each Reporting Person disclaims beneficial ownership of such shares except to the extent of its pecuniary interest therein, and the inclusion of these securities in this report shall not be deemed an admission that any reporting person is the beneficial owner of such shares for purposes of the Securities Exchange Act of 1934 or for any other purpose.</footnote>
        <footnote id="F5">Each share of Series F Convertible Preferred Stock shall automatically convert into Common Stock on a 1:1 basis immediately prior to the completion of the Issuer's initial public offering of Class A Common Stock and has no expiration date.</footnote>
        <footnote id="F6">Each share of Series G Convertible Preferred Stock shall automatically convert into Common Stock on a 1:1 basis immediately prior to the completion of the Issuer's initial public offering of Class A Common Stock and has no expiration date.</footnote>
        <footnote id="F7">Each share of Series H Convertible Preferred Stock shall automatically convert into Common Stock on a 1:1 basis immediately prior to the completion of the Issuer's initial public offering of Class A Common Stock and has no expiration date.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Karen Ellerbe, a Director of SVF Fast (Cayman) Limited</signatureName>
        <signatureDate>2020-12-08</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Brian Wheeler, General Counsel of SB Investment Advisers (UK) Limited, Manager of SoftBank Vision Fund (AIV M2) L.P.</signatureName>
        <signatureDate>2020-12-08</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Brian Wheeler, General Counsel of SB Investment Advisors (UK) Limited</signatureName>
        <signatureDate>2020-12-08</signatureDate>
    </ownerSignature>
</ownershipDocument>
