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

    <schemaVersion>X0407</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2023-03-20</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001635088</issuerCik>
        <issuerName>Roivant Sciences Ltd.</issuerName>
        <issuerTradingSymbol>ROIV</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001716729</rptOwnerCik>
            <rptOwnerName>SVF Investments (UK) Ltd</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>69 GROSVENOR STREET</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>0001699940</rptOwnerCik>
            <rptOwnerName>SoftBank Vision Fund L.P.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>AZTEC GROUP HOUSE 11-15 SEATON PLACE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>ST. HELIER</rptOwnerCity>
            <rptOwnerState>Y9</rptOwnerState>
            <rptOwnerZipCode>JE4 0QH</rptOwnerZipCode>
            <rptOwnerStateDescription>JERSEY</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001716727</rptOwnerCik>
            <rptOwnerName>SVF Holdings (UK) LLP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>69 GROSVENOR STREET</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>0001731509</rptOwnerCik>
            <rptOwnerName>SB INVESTMENT ADVISERS (UK) LTD</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>69 GROSVENOR STREET</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>

    <aff10b5One>0</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Shares</value>
            </securityTitle>
            <transactionDate>
                <value>2023-03-20</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>12000000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>8.00</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>83031667</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote</value>
                    <footnoteId id="F1"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Securities held of record by SVF Investments (UK) Limited (&quot;SVF Investments&quot;). Softbank Vision Fund L.P. is the managing member of SVF Holdings (UK) LLP, which is the sole owner of SVF Investments. SB Investment Advisers (UK) Limited (&quot;SBIA UK&quot;) has been appointed as the alternative investment fund manager (&quot;AIFM&quot;) of SoftBank Vision Fund L.P. SBIA UK is authorized and regulated by the UK Financial Conduct Authority and is exclusively responsible for making all decisions related to the acquisition, structuring, financing and disposal of SoftBank Vision Fund L.P.'s investments.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>SVF Investments (UK) Limited, By: SB Investment Advisers (UK) Limited, its manager, By: /s/ Amanda Sanchez-Barry, General Counsel</signatureName>
        <signatureDate>2023-03-22</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>SVF Holdings (UK) LLP, By: SB Investment Advisers (UK) Limited, its manager, By: /s/ Amanda Sanchez-Barry, General Counsel</signatureName>
        <signatureDate>2023-03-22</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>SoftBank Vision Fund L.P., By: SB Investment Advisers (UK) Limited, its manager, By: /s/ Amanda Sanchez-Barry, General Counsel</signatureName>
        <signatureDate>2023-03-22</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>SB Investment Advisers (UK) Limited, By: /s/ Amanda Sanchez-Barry, General Counsel</signatureName>
        <signatureDate>2023-03-22</signatureDate>
    </ownerSignature>
</ownershipDocument>
