In　this　work,　a　novel　homogeneous　electrochemical　(HEC)　sensing　strategy　was　developed　for　carcinoembryonic　antigen　(CEA)　detection,　addressing　limitations　of　traditional　electrochemical　platforms　that　necessitate　complex　electrode　modifications　and　receptor　immobilization　protocols.　This　approach　integrates　platinum　nanoparticle-loaded　UiO-66　metal-organic　frameworks　(Pt/UiO)　as　an　oxidase-like　nanozyme　with　CEA-specific　aptamer　(Apt)　as　recognition　element,　establishing　a　target-responsive　catalytic　mechanism.　In　solution-phase　operation,　the　Pt/UiO　nanozyme　facilitates　the　oxidation　of　1,2-diaminobenzene　into　electroactive　diaminophenazine　(DAP),　generating　measurable　reduction　current　at　unmodified　electrode.　Apt　adsorption　onto　Pt/UiO　surfaces　effectively　inhibits　this　enzymatic　activity　through　steric　hindrance,　resulting　in　current　suppression　proportional　to　Apt　coverage.　The　presence　of　CEA　induces　specific　Apt-CEA　binding,　resulting　Apt　away　from　the　nanozyme　surface　and　restoring　catalytic　activity　in　a　concentration-dependent　manner.　Optimization　of　experimental　parameters　(e.g.,　nanozyme　concentration,　incubation　time)　enabled　the　sensor　to　achieve　a　detection　limit　of　3　pg　mL−1　with　a　linear　range　spanning　0.01–11　ng　mL−1,　demonstrating　potential　for　point-of-care　applications　in　tumor　biomarker　analysis.　©　2025