<SEC-DOCUMENT>0001628280-17-008550.txt : 20170810
<SEC-HEADER>0001628280-17-008550.hdr.sgml : 20170810
<ACCEPTANCE-DATETIME>20170810202318
ACCESSION NUMBER:		0001628280-17-008550
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20170810
FILED AS OF DATE:		20170810
DATE AS OF CHANGE:		20170810

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Marsal Karel J.
		CENTRAL INDEX KEY:			0001705942

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-35231
		FILM NUMBER:		171022755

	MAIL ADDRESS:	
		STREET 1:		600 B STREET, SUITE 100
		CITY:			SAN DIEGO
		STATE:			CA
		ZIP:			92101

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			MITEK SYSTEMS INC
		CENTRAL INDEX KEY:			0000807863
		STANDARD INDUSTRIAL CLASSIFICATION:	COMPUTER PERIPHERAL EQUIPMENT, NEC [3577]
		IRS NUMBER:				870418827
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0930

	BUSINESS ADDRESS:	
		STREET 1:		600 B STREET
		STREET 2:		SUITE 100
		CITY:			SAN DIEGO
		STATE:			CA
		ZIP:			92101
		BUSINESS PHONE:		619-269-6800

	MAIL ADDRESS:	
		STREET 1:		600 B STREET
		STREET 2:		SUITE 100
		CITY:			SAN DIEGO
		STATE:			CA
		ZIP:			92101
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wf-form4_150241098392622.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2017-08-10</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000807863</issuerCik>
        <issuerName>MITEK SYSTEMS INC</issuerName>
        <issuerTradingSymbol>MITK</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001705942</rptOwnerCik>
            <rptOwnerName>Marsal Karel J.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>600 B STREET, SUITE 100</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SAN DIEGO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>92101</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Chief Operating Officer</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable></nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Performance Restricted Stock Units</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2017-08-10</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>200000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F3"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Sock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>200000.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>200000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Each performance restricted stocked unit represents a contingent right to receive one share of Mitek common stock. No performance restricted stock unit vests (and thus no shares of common stock are issued) unless the fair market value of Mitek's common stock at the end of a set performance period or upon a change of control during such performance period is equal to or exceeds $16.00 per share. To incentivize relative performance of Mitek's stock price, reduced vesting could occur in the event Mitek's common stock price appreciation during the performance period underperforms against the Russell 2000 Index.</footnote>
        <footnote id="F2">The fair market value of Mitek's common stock at the end of the performance period is determined based on the average closing price of Mitek's common stock for the last 20 trading days of the performance period. The fair market value of Mitek's common stock upon a change of control shall equal (i) the consideration to be received by Mitek's stockholders with respect to one share of Mitek common stock upon such change of control or (ii) upon an asset sale, the consideration that would be distributable to Mitek's stockholders with respect to each share of Mitek common stock if Mitek distributed all of the consideration received in connection with the asset sale to its stockholders, less adjustments for debt, expenses and other amounts.</footnote>
        <footnote id="F3">The vesting date for the performance restricted stock units, if such a date occurs, will not be determined until the end of the performance period or upon a change of control during the performance period. The performance period begins on March 1, 2017 and ends on the date that is 25 trading days after the first filing of an Annual Report on Form 10-K or Quarterly Report on Form 10-Q by Mitek following September 30, 2019.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Trevor Renfield, by Power of Attorney</signatureName>
        <signatureDate>2017-08-10</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
