Electrochemical ozone evolution reaction (OZER) offers sustainable in-situ O3 generation over corona discharge, with Ni-Sb-SnO2 emerging as a promising electrocatalyst. However, the reason why trace Ni doping drastically enhances OZER selectivity over Sb-SnO2 remains unclear due to the complex OZER mechanism involving Ni and Sb interplays. Here, in-situ/ex-situ X-ray spectroscopy combined with comprehensive density functional theory (DFT) modeling reveals Ni's promotional role in OZER selectivity. We identify a dynamic hydroxyl bridge (ObridH) pathway distinct from conventional adsorbate evolution and lattice oxygen mechanisms. Ni dopant elevates the O 2p level, facilitating oxygen vacancy formation and dynamic ObridH stabilization. The ObridH species lowers the barrier for potential-determining *OH deprotonation, inducing unconventional proton dynamics reflected in negative pH-dependence. Characterization-guided DFT models derive a comprehensive eight-step mechanism and clarify distinct electronic roles of Ni and Sb. These findings advance mechanistic understanding of OZER and guide rational design of SnO2-based catalysts.​