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

    <schemaVersion>X0206</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2019-02-01</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001447669</issuerCik>
        <issuerName>TWILIO INC</issuerName>
        <issuerTradingSymbol>TWLO</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001534338</rptOwnerCik>
            <rptOwnerName>Bessemer Venture Partners VII L.P.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O BESSEMER VENTURE PARTNERS</rptOwnerStreet1>
            <rptOwnerStreet2>1865 PALMER AVENUE, SUITE 104</rptOwnerStreet2>
            <rptOwnerCity>LARCHMONT</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10538</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001407577</rptOwnerCik>
            <rptOwnerName>Bessemer Venture Partners VII Institutional L.P.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O BESSEMER VENTURE PARTNERS</rptOwnerStreet1>
            <rptOwnerStreet2>1865 PALMER AVENUE, SUITE 104</rptOwnerStreet2>
            <rptOwnerCity>LARCHMONT</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10538</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001459524</rptOwnerCik>
            <rptOwnerName>BVP VII SPECIAL OPPORTUNITY FUND LP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O BESSEMER VENTURE PARTNERS</rptOwnerStreet1>
            <rptOwnerStreet2>1865 PALMER AVENUE, SUITE 104</rptOwnerStreet2>
            <rptOwnerCity>LARCHMONT</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10538</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001677269</rptOwnerCik>
            <rptOwnerName>15 Angels LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O BESSEMER VENTURE PARTNERS</rptOwnerStreet1>
            <rptOwnerStreet2>1865 PALMER AVE., SUITE 104</rptOwnerStreet2>
            <rptOwnerCity>LARCHMONT</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10538</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001540731</rptOwnerCik>
            <rptOwnerName>Deer VII &amp; Co. L.P.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O BESSEMER VENTURE PARTNERS</rptOwnerStreet1>
            <rptOwnerStreet2>1865 PALMER AVENUE, SUITE 104</rptOwnerStreet2>
            <rptOwnerCity>LARCHMONT</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10538</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001540726</rptOwnerCik>
            <rptOwnerName>Deer VII &amp; Co. Ltd.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O BESSEMER VENTURE PARTNERS</rptOwnerStreet1>
            <rptOwnerStreet2>1865 PALMER AVENUE, SUITE 104</rptOwnerStreet2>
            <rptOwnerCity>LARCHMONT</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10538</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Class B Common Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0.00</value>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F1"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Class A Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>6169303</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnotes</value>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Each share of Class B Common Stock is convertible without payment or consideration into one share of Class A Common Stock at the option of the holder and has no expiration date.</footnote>
        <footnote id="F2">Represents 1,935,805 shares of Class B Common Stock held by Bessemer Venture Partners VII L.P. (&quot;BVP VII&quot;), 846,915 shares of Class B Common Stock held by Bessemer Venture Partners VII Institutional L.P. (&quot;BVP VII Inst&quot;), 3,266,672 shares of Class B Common Stock held by BVP VII Special Opportunity Fund L.P. (&quot;BVP VII SOF&quot;) and 119,911 shares of Class B Common Stock held by 15 Angels LLC, a wholly-owned subsidiary of BVP VII Inst (&quot;BVP 15A&quot; and, together with BVP VII, BVP VII Inst and BVP VII SOF, the &quot;BVP VII Funds&quot;).</footnote>
        <footnote id="F3">Deer VII &amp; Co. Ltd. (&quot;Deer VII Ltd.&quot;) is the general partner of Deer VII &amp; Co. L.P. (&quot;Deer VII L.P.&quot; and, together with the BVP VII Funds and Deer VII Ltd., the &quot;BVP VII Entities&quot;), which is the general partner of each of BVP VII, BVP VII Inst and BVP VII SOF. Deer VII Ltd. and VII Deer L.P. disclaim beneficial ownership of the securities held by the BVP VII Funds, and this report shall not be deemed an admission that Deer VII Ltd. and Deer VII L.P. are the beneficial owners of such securities, except to the extent of their pecuniary interest therein, if any, by virtue of their direct and indirect general partner interests in the BVP VII Funds.</footnote>
        <footnote id="F4">Byron Deeter is a director of Twilio Inc. (&quot;Twilio&quot;).  Mr. Deeter also is a director of Deer VII Ltd. Mr. Deeter also is a director of Deer VIII &amp; Co. Ltd. (&quot;Deer VIII Ltd.&quot;), which is the general partner of Deer VIII &amp; Co. L.P. (&quot;Deer VIII L.P.&quot;), which is the general partner of Bessemer Venture Partners VIII Institutional L.P. (&quot;BVP VIII Inst&quot;) and Bessemer Venture Partners VIII L.P. (&quot;BVP VIII&quot; and, together with BVP VIII Inst, Deer VIII Ltd. and Deer VIII L.P., the &quot;BVP VIII Entities&quot;).  Mr. Deeter serves as a representative of the BVP VII Entities and the BVP VIII Entities on the Board of Directors of Twilio.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Scott Ring, General Counsel, Deer VII &amp; Co. Ltd., the General Partner of Deer VII &amp; Co. L.P., the General Partner of Bessemer Venture Partners VII L.P.</signatureName>
        <signatureDate>2019-02-01</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Scott Ring, General Counsel, Deer VII &amp; Co. Ltd., the General Partner of Deer VII &amp; Co. L.P., the General Partner of Bessemer Venture Partners VII Institutional L.P.</signatureName>
        <signatureDate>2019-02-01</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Scott Ring, General Counsel, Deer VII &amp; Co. Ltd., the General Partner of Deer VII &amp; Co. L.P., the General Partner of BVP VII Special Opportunity Fund L.P.</signatureName>
        <signatureDate>2019-02-01</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Scott Ring, General Counsel, Deer VII &amp; Co. Ltd.</signatureName>
        <signatureDate>2019-02-01</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Scott Ring, General Counsel, Deer VII &amp; Co. Ltd., the General Partner of Deer VII &amp; Co. L.P.</signatureName>
        <signatureDate>2019-02-01</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Scott Ring, Authorized Person of 15 Angels LLC</signatureName>
        <signatureDate>2019-02-01</signatureDate>
    </ownerSignature>
</ownershipDocument>
