The selective oxidation of aromatic C–H bonds to high value-added oxygenated products with molecular oxygen remains a key challenge in heterogeneous catalysis. Eligible heterogeneous catalysts are pursued and the reaction mechanism is hotly debated. Herein, we report that zeolite-encaged single-site cobalt ions can efficiently catalyze the model reaction of ethylbenzene aerobic oxidation to acetophenone, outperforming the industrial benchmark catalyst cobalt naphthenate under identical conditions. The self-accelerating phenomenon is observed in the progress of ethylbenzene aerobic oxidation, corresponding to the self-adjusted reaction pathway as revealed by kinetic studies and density functional theory calculations. The formation of reactive O* species on Co sites, resembling the well-known α-O on Fe sites, is identified to be responsible for the self-adjusted reaction pathway of aromatic C–H bond oxidation.