Nanozyme-based　electrochemical　biosensors　have　emerged　as　an　alternative　to　enzyme-based　biosensors　for　next-generation　bioanalysis.　However,　potential　antibody　modifications　limit　the　catalytic　sites　of　the　nanozyme,　thereby　reducing　sensor　sensitivity.　Here,　a　sensitive　method　for　determining　carcinoembryonic　antigen　(CEA)　was　developed.　It　involved　coupling　a　cascade　enzyme　-　enzyme　-　like　catalytic　reaction　using　Fe　-　Co　Prussian　blue　analog　nanozymes　with　high　peroxidase　-　like　activity　(79.42　U　mg−1).　Briefly,　the　transduction　of　biological　signals　to　chemical　signals　was　achieved　through　the　strategy　centered　on　catalytic　electroactive　probes.　Thereafter,　with　the　assistance　of　the　microelectrochemical　workstation,　the　output　of　signals　was　realized.　The　platform　exhibited　an　ultra-wide　range　of　0.020–100　ng　mL−1　and　a　detection　limit　of　0.013　ng　mL−1　CEA,　which　was　mainly　attributed　to　the　excellent　peroxidase　activity,　good　conductivity,　and　synergistic　amplification　of　current　signals　of　synthesized　nanozymes.　In　addition,　the　modification-free　features　greatly　reduced　the　complexity　of　the　bioassay　and　significantly　improves　its　portability　and　cost-effectiveness.　Overall,　this　study　advances　the　development　of　nanozymes　and　their　electrochemical　biosensing　applications　and　is　expected　to　extend　to　the　development　of　miniaturized　devices　in　direct　detection　environments.　©　2025　Elsevier　B.V.