Bidirectional　electron　transfer　biofilms　(BETB)　could　efficiently　reduce　nitrate　without　accumulating　nitrite,　representing　a　promising　biological　electrochemical　denitrification　technology.　This　study　utilized　iron　phthalocyanine　modified　carbon　felt　(FePc-CF)　to　enrich　electroactive　bacteria,　constructing　a　long-term　stable　FePc-BETB.　Its　nitrate　removal　rate　reached　91%,　far　exceeding　the　traditional　nitrate-reducing　biocathode　(45%)　and　Con-BETB　(46%).　The　dissimilatory　nitrate　reduction　to　ammonium　(DNRA)　dominated　nitrate　reduction　in　FePc-BETB,　consuming　35%　of　the　total　electrons.　Additionally,　FePc-BETB　effectively　reduced　the　accumulation　of　NO2−-N　and　N2O.　Electrochemical　analysis　demonstrated　FePc-BETB　exhibited　stronger　electrochemical　activity　and　electron　transfer　capability.　Mediated　electron　transfer　(MET)　enhanced　by　increased　extracellular　humic　acid　in　FePc-BETB　favored　the　electron　supplement　for　nitrate　removal.　The　relative　abundance　of　nrfA,　marker　of　the　DNRA,　increased　significantly.　This　study　provided　new　insights　into　regulating　denitrification　and　DNRA　pathways　and　treating　nitrate　wastewater　lacking　electron　donors.　©　2025　Elsevier　Ltd