Abstract: Heteroatom-doped carbon is considered a promising alternative to commercial Pt/C as an efficient catalyst for the oxygen reduction reaction (ORR). This study presents the synthesis of iron-loaded, sulfur and nitrogen co-doped carbon (Fe/SNC) via in situ incorporation of 2-aminothiazole molecules into zeolitic imidazolate framework-8 (ZIF-8) through coordination between metal ions and organic ligands. Sulfur and nitrogen doping in carbon supports effectively modulates the electronic structure of the catalyst, increases the Brunauer–Emmett–Teller surface area, and exposes more Fe–N_x active centers. Fe-loaded, S and N co-doped carbon with Fe/S molar ratio of 1:10 (Fe/SNC-10) exhibits a half-wave potential of 0.902 V vs. RHE. After 5000 cycles of cyclic voltammetry, its half-wave potential decreases by only 20 mV vs. RHE, indicating excellent stability. Due to sulfur’s lower electronegativity, the electronic structure of the Fe–N_x active center is modulated. Additionally, the larger atomic radius of sulfur introduces defects into the carbon support. As a result, Fe/SNC-10 demonstrates superior ORR activity and stability in alkaline solution compared with Fe-loaded N-doped carbon (Fe/NC). Furthermore, the zinc–air battery assembled with the Fe/SNC-10 catalyst shows enhanced performance relative to those assembled with Fe/NC and Pt/C catalysts. This work offers a novel design strategy for advanced energy storage and conversion applications.