Abstract The in‐depth understanding of local atomic environment–property relationships of p‐block metal single‐atom catalysts toward the 2 e − oxygen reduction reaction (ORR) has rarely been reported. Here, guided by first‐principles calculations, we develop a heteroatom‐modified In‐based metal–organic framework‐assisted approach to accurately synthesize an optimal catalyst, in which single In atoms are anchored by combined N,S‐dual first coordination and B second coordination supported by the hollow carbon rods (In SAs/NSBC). The In SAs/NSBC catalyst exhibits a high H 2 O 2 selectivity of above 95 % in a wide range of pH. Furthermore, the In SAs/NSBC‐modified natural air diffusion electrode exhibits an unprecedented production rate of 6.49 mol peroxide g catalyst −1 h −1 in 0.1 M KOH electrolyte and 6.71 mol peroxide g catalyst −1 h −1 in 0.1 M PBS electrolyte. This strategy enables the design of next‐generation high‐performance single‐atom materials, and provides practical guidance for H 2 O 2 electrosynthesis.