An　ultrasensitive　competitive-type　electrochemiluminescence　immunoassay　for　the　mycotoxin　zearalenone　is　described.　The　method　is　based　on　the　use　of　(a)　a　mimotope　peptide　that　was　selected　from　a　phage　displayed　peptide　library　and　used　to　substitute　ZEN　for　designing　the　competitive　assay;　(b)　NiFe2O4　nanotubes　with　large　specific　surface　area　loaded　with　the　ECL　probe　Ru(bpy)(3)(2+);　and　(c)　poly(vinylpyrrolidone)　(PVP)-assisted　synthesis　of　TiO2　mesocrystals　that　acts　as　the　sensing　platform　and　support　for　antibody　immobilization.　Under　the　optimized　conditions　and　at　an　ECL　working　potential　of　1.1　V,　a　linear　response　is　found　for　ZEN　in　the　0.1　to　1.0　x　10(-5)　ng　center　dot　mL(-1)　concentration　range　with　a　detection　limit　as　low　as　3.3　fg　center　dot　mL(-1).　Graphical　abstract　An　ultrasensitive　competitive-type　electrochemiluminescence　(ECL)　immunosensor　based　on　mimotope　peptide　was　constructed　for　the　detection　of　Zearalenone.