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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2019-04-12</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001649989</issuerCik>
        <issuerName>Outlook Therapeutics, Inc.</issuerName>
        <issuerTradingSymbol>OTLK</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001716335</rptOwnerCik>
            <rptOwnerName>BioLexis Pte Ltd.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>36 ROBINSON ROAD</rptOwnerStreet1>
            <rptOwnerStreet2>#13-01 CITY HOUSE</rptOwnerStreet2>
            <rptOwnerCity>SINGAPORE</rptOwnerCity>
            <rptOwnerState>U0</rptOwnerState>
            <rptOwnerZipCode>068877</rptOwnerZipCode>
            <rptOwnerStateDescription>SINGAPORE</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001717437</rptOwnerCik>
            <rptOwnerName>Pillai Arun Kumar</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>#30, 1ST MAIN</rptOwnerStreet1>
            <rptOwnerStreet2>J.P. NAGAR 3RD PHASE</rptOwnerStreet2>
            <rptOwnerCity>BANGALORE</rptOwnerCity>
            <rptOwnerState>K7</rptOwnerState>
            <rptOwnerZipCode>560078</rptOwnerZipCode>
            <rptOwnerStateDescription>INDIA</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001717441</rptOwnerCik>
            <rptOwnerName>Sukhtian Ghiath M.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>7TH CIRCLE, ZAHRAN STREET</rptOwnerStreet1>
            <rptOwnerStreet2>ZAHRAN PLAZA BLDG, 4TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>AMMAN</rptOwnerCity>
            <rptOwnerState>M2</rptOwnerState>
            <rptOwnerZipCode>11844</rptOwnerZipCode>
            <rptOwnerStateDescription>JORDAN</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2019-04-12</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>3636364</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>2.75</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>11857676</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Warrant (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>2.90</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2019-04-12</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>3636364</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F4"/>
            </exerciseDate>
            <expirationDate>
                <value>2020-07-12</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>3636364</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3636364</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Warrant (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>2.90</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2019-04-12</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>3636364</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F4"/>
            </exerciseDate>
            <expirationDate>
                <value>2024-04-12</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>3636364</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3636364</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">The Common Stock together with the 15-month and 5-year Common Stock Warrants reported in Table II herein were acquired by BioLexis Pte Ltd (&quot;BioLexis&quot;) in the Issuers combined public offering of the Common Stock and accompanying Warrants. The purchase price for the combined offering of the shares of Common Stock and the accompanying Warrants is $2.75 per share.</footnote>
        <footnote id="F2">These securities are held of record by BioLexis. Tenshi Life Sciences Private Limited (&quot;Tenshi&quot;), a private investment vehicle controlled by Arun Kumar Pillai (&quot;Kumar&quot;), and GMS Pharma (Singapore) Pte. Limited (&quot;GMS Pharma&quot;), a private investment company and wholly-owned subsidiary of GMS Holdings, are the 50:50 beneficial owners of BioLexis, in which each of Tenshi and GMS Pharma owns 50% of the outstanding voting shares. Kumar, a natural person, is the holder of a controlling interest in Tenshi. Ghiath M. Sukhtian (&quot;Ghiath Sukhtian&quot;), a natural person, is the holder of a controlling interest in GMS Holdings, which is the holder of a controlling interest in GMS Pharma.</footnote>
        <footnote id="F3">By virtue of the relationships described above in Footnote 2, Kumar and Ghiath Sukhtian may be deemed to have voting and investment power with respect to the securities held by BioLexis noted above and as a result may be deemed to beneficially own such securities for purposes of Rule 13d-3 under the Securities Exchange Act of 1934, as amended (the &quot;Exchange Act&quot;). The Reporting Persons disclaim beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Exchange Act, except to the extent of its or his pecuniary interest therein, if any. BioLexis has designated four representatives to serve on the Issuer's board of directors. This report shall not be deemed an admission that any of the Reporting Persons are the beneficial owner of such securities for the purpose of Section 16 of the Exchange Act, or for any other purpose.</footnote>
        <footnote id="F4">Immediately exercisable.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Faisal G. Sukhtian</signatureName>
        <signatureDate>2019-04-16</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Arun Kumar Pillai</signatureName>
        <signatureDate>2019-04-16</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Ghiath M. Sukhtian</signatureName>
        <signatureDate>2019-04-16</signatureDate>
    </ownerSignature>
</ownershipDocument>
