Single Fe atom dispersed carbon nanostructures show promising oxygen reduction reaction (ORR) activities for renewable energy applications. Nevertheless, the microenvironment of the single Fe atoms needs to be further engineered to optimize the catalytic performance, which is challenging. In this work, we develop a NaCl-template pyrolysis method to fabricate single Fe atom catalysts with atomically dispersed Fe–heteroatom (N, S) bridge sites anchored on carbon nanosheets. The N and S coordinated Fe atomic sites (FeN₃S) are found to induce charge redistribution, lowering the binding strength of oxygenated reaction intermediates and leading to fast reaction kinetics and good oxygen reduction activity. Our work provides an effective method to regulate the microenvironment of single-atom catalysts for optimizing electrocatalytic performance.