The sluggish H2O oxidation kinetics on photoanodes severely obstructs the overall solar-to-energy efficiency of photoelectrochemical (PEC) cells. Herein, we find a 10 to 55-fold increase of photocurrent by conducting ammonia oxidation reaction (AOR) on hematite (α-Fe2O3) photoanodes under near-neutral pH (9~11) and moderate applied potentials (1.0~1.4 VRHE) compared to H2O oxidation. By rate law analysis and operando spectroscopic studies, we confirm the non-radical nucleophilic attack of NH3 molecules on high-valent surface Fe-O species (e.g., FeIV=O) and Fe-N species that produces NOx- and N2, respectively, which overwhelms the nucleophilic attack of H2O on surface FeIV=O and contributes to a high Faradaic efficiency of above 80% for AOR. This work reveals a novel non-radical nucleophilic attack strategy, which is significantly different from the conventional indirect radical-mediated AOR mechanism, for the rational design of high-performance AOR photoelectrocatalysts.