In　this　study,　a　mimotope　peptide-based　non-toxic　photoelectrochemical　(PEC)　competitive　enzyme-linked　immunoassay　(ELISA)　was　established　for　ultrasensitive　detection　of　zearalenone　(ZEN)　with　dual-signal　readout.　Using　the　phage　display　technique　(PDT),　a　mimotope　peptide　of　ZEN　could　be　harvested　by　selecting　a　peptide　from　a　phage-display　peptide　library,　which　avoided　using　mycotoxin　itself　and　minimized　potential　damage　to　operators.　The　tyramine-modified　rutile　TiO2　mesocrystals　(Tyr-RMC)　with　outstanding　PEC　properties　were　utilized　as　reporter　units　to　label　the　mimotope　peptide.　The　fabricated　peptide@Tyr-RMC　probe　could　anchor　on　the　antibody-modified　electrode　via　competitive　immune　recognition　of　free　target　ZEN.　When　subjected　to　catalysis　of　HRP-H2O2,　the　Tyr-RMC　composite　was　deposited　at　the　enzyme　reaction　site,　causing　rolling　circle　extension　of　the　reporter　unit　chains.　By　merit　of　the　brilliant　signal　amplification　effect　of　tyramine　signal　amplification　(TSA),　dramatically　enhanced　photocurrent　response　and　enormously　increased　electrochemical　impedance　could　be　determined.　Combining　all　of　these　advantages,　the　developed　dual-signal　readout　non-toxicity　immunoassay　could　effectively　decrease　environmental　interference.　Also,　the　designed　dual-signal　readout　biosensor　demonstrated　a　wide　linear　range　between　10-6　and　1　ng　mL-1　with　a　low　detection　limit　of　1　×　10-6　ng　mL-1,　which　provides　a　valuable　reference　for　developing　highly　efficient,　secure　and　sensitive　detection　methods　and　indicates　promising　applicability　in　food　testing.　©　2019　The　Royal　Society　of　Chemistry.