The energy‐free activation of ambient molecular oxygen (O ₂ ) to singlet oxygen ( ¹ O ₂ ) under neutral conditions is highly desirable for green oxidation chemistry, yet remains fundamentally limited by sluggish proton‐coupled *OOH formation and desorption. Here, we engineer an interfacial proton‐relay microenvironment between MoS ₂ and CuCl that enables self‐driven O ₂ ‐to‐ ¹ O ₂ conversion without external energy inputs. Electron‐deficient sulfur sites act as a proton reservoir by forming S‐H _ads species, facilitating directional proton migration through Cu‐S‐Mo channels to activate adsorbed O ₂ on electron‐rich Cu sites. This coupled electron‐proton relay accelerates *OOH hydrogenation while maintaining moderate *O2/*OOH binding, effectively suppressing O─O bond cleavage and favoring a 1O2‐dominated pathway. As a result, the system achieves quantitative pollutant removal and sustained operation for over 16 h in pilot‐scale membrane filtration. This interfacial design is broadly applicable to transition metal sulfides, offering a general strategy to overcome proton‐transfer limitations and advance autonomous catalytic platforms for sustainable oxidation and environmental remediation.