Electrochemical two‐electron oxygen reduction reaction (2 e− ORR) to produce hydrogen peroxide (H2O2) is a promising alternative to the energetically intensive anthraquinone process. However, there remain challenges in designing 2 e− ORR catalysts that meet the application criteria. Here, we successfully adopt a microwave‐assisted mechanochemical‐thermal approach to synthesize hexagonal phase SnO2 (h‐SnO2) nanoribbons with largely exposed edge structures. In 0.1 M Na2SO4 electrolyte, the h‐SnO2 catalysts achieve the excellent H2O2 selectivity of 99.99 %. Moreover, when employed as the catalyst in flow cell devices, they exhibit a high yield of 3885.26 mmol g−1 h−1. The enhanced catalytic performance is attributed to the special crystal structure and morphology, resulting in abundantly exposed edge active sites to convert O2 to H2O2, which is confirmed by density functional theory calculations. A new hexagonal phase SnO2 nanoribbon with abundant edge‐active sites has been successfully synthesized by microwave‐assisted mechanochemical‐thermal method. Due to its special structure and morphology, the h‐SnO2 catalysts exhibit near 100 % H2O2 selectivity.