Developing high-efficiency and low-cost cathodic oxygen reduction reaction catalyst for large-scale application of proton exchange membrane fuel cell is highly significant but still full of challenges. Herein, well defined Fe–N co-doped hollow carbon nanopolyhedra catalyst, with exclusive Fe–N_x active sites derived from the addition of C3N4 in the precursor, have been prepared by a facile and effective strategy, where hollow ZIF-8 is first synthesized by a chemical etching process, followed by impregnating with ferric acetylacetonate and g-C₃N₄, and pyrolyzing in Ar atmosphere. The catalyst inherits the good polyhedra morphology from its precursor, and the resulting optimal catalyst exhibits superior ORR performance in both acidic and alkaline mediums, with a half-wave potential of 0.78 V comparable to that of commercial Pt/C catalysts in acidic medium, and a half-wave potential of 0.85 V, ca. 30 mV more positive than that of commercial Pt/C catalyst in alkaline medium, making it one of the best doped carbon catalysts in an acidic and alkaline medium up to now; It is important that our hollow nanopolyhedra catalyst exhibits superior stability both in acidic and alkaline mediums, superior to commercial Pt/C. Furthermore, in the H₂-O₂ single PEM cell test, the MEA with our optimal hollow nanopolyhedra catalysts as cathodeachieved a current density of 700 mA cm⁻² @ 0.6 V and 400 mA cm⁻² @ 0.7 V, which is one the best PEMFC’s performance reported for doped carbon cathode. Combining ⁵⁷Fe Mössbauer spectroscopy and X-ray photoelectron spectroscopy results, we ascribe the outstanding performance of our catalyst to the homogeneous distributions of high-density of Fe–N_x active sites (D1: FeN₄/C and D3: N–Fe^IIN₂₊₂…N_prot/C) and pyridinic-N, caused by the addition of C₃N₄.