Strengthening the oxide–metal interfacial synergistic interaction in nanocatalysts is identified as potential strategy to boost intrinsic activities and the availability of active sites by regulating the surface/interface environment of catalysts. Herein, the SnO₂/PtNi concave nanocubes (CNCs) enclosed by high-index facets (HIFs) with tunable SnO₂ composition are successfully fabricated through combining the hydrothermal and self-assembly method. The interfacial interaction between ultrafine SnO₂ nanoparticles and PtNi with HIFs surface structure is characterized by analytical techniques. The as-prepared 0.20%SnO₂/PtNi catalyst exhibits extraordinarily high catalytic performance for ethylene glycol electrooxidation (EGOR) in acidic conditions with specific activity of 3.06 mA/cm², which represents 6.2-fold enhancement compared with the state-of-the-art Pt/C catalyst. Additionally, the kinetic study demonstrates that the strong interfacial interaction between SnO₂ and PtNi not only degrades the activation energy barrier during the process of EGOR but also enhances the CO-resistance ability and long-term stability. This study provides a novel perspective to construct highly efficient and stable electrocatalysts for energy conversions.