Background:　Cardiac　troponin　I　(cTnI)　is　a　crucial　diagnosis　biomarker　for　acute　myocardial　infarction　(AMI).　Early　accurate　determination　of　the　concentration　of　cTnI　significantly　decreases　the　death　rate　of　AMI.　Compared　with　classic　methods,　dual-mode　sensors　for　cTnI　determination　could　help　reduce　the　false　positive　rate.　Result:　In　this　work,　an　ultrathin　Fe-MOF-74　nanosheet　with　fluorescence　properties　and　peroxidase　mimic　activity　was　synthesized　for　the　first　time.　Applying　this　nanosheet,　a　novel　dual-mode　sensor　was　developed　to　quantify　cTnI　in　human　serum.　The　ultrathin　Fe-MOF-74　nanosheets　catalyze　the　decomposition　of　hydrogen　peroxide　produced　by　glucose　oxidase　(GOx)-triggered　enzyme-linked　immunosorbent　assay　(ELISA)　applying　cTnI　as　an　antigen　target,　to　generate　reactive　oxygen　species　(ROS).　3,3′,5,5′-tetramethylbenzidine　(TMB)　can　be　oxidized　by　the　generated　free　radicals,　which　simultaneously　lead　to　the　fluorescence　quench　of　Fe-MOF-74　due　to　the　inner　filter　effect　(IFE).　The　correlation　between　the　morphology　of　Fe-MOF-74　and　its　fluorescence　intensity　and　peroxidase　mimic　activity　was　also　investigated.　Significance:　The　sensors　exhibited　linearity　with　the　concentration　of　cTnI　in　10–2000　pg　mL−1　in　both　the　fluorescence　and　visual　mode　with　the　detection　limit　of　6.4　pg　mL−1　and　8.4　pg　mL−1,　respectively.　It　presenting　good　selectivity　and　anti-interference　ability,　can　provide　accurate　and　precise　results　in　testing　the　concentration　of　cTnI　in　serum　samples　from　patients　in　hospitals.　It　could　be　applied　in　the　early　diagnosis　of　AMI　to　reduce　the　incidence,　disability,　and　mortality　rates.　©　2025　Elsevier　B.V.