The attainment of simultaneously efficient clean energy production and environmental pollution treatment has been a research focus yet still challenging. Herein, S-doped N-deficient carbon nitride (S-g-C3N4-N) is ingenously synthesized for photocatalytic two-electron oxygen reduction reaction (2e− ORR) for hydrogen peroxide (H2O2) generation and simultaneous degradation organic pollutants (BPA). Experimental/theoretical studies show that S doping and N defects endow S-g-C3N4-N with improved light absorption, carrier separation and transport, and O2 adsorption and activation capacity compared to g-C3N4. On this basis, S-g-C3N4-N has an excellent H2O2 yield (221.68 μM) and BPA degradation rate (0.0596 min−1), far exceeding the pristine g-C3N4. More notably, the existence of BPA synergistically improves the production of H2O2, which is attributed to the fact that BPA degradation consumes many photogeneration holes and promotes carrier separation, thus boosting 2e− ORR to synthesize H2O2. Our study offers novel guidance for efficient photocatalytic generation of H2O2 and the simultaneous breakdown of organic pollutants.