<p>Electro-reforming of biomass into value-added chemicals offers a sustainable approach for future energy developments. However, noble metal catalysts toward glucose electrooxidation suffer from deactivation, poor selectivity, and limited power density. Here, we present Au^δ−-Cu^δ+ sites in AuCu alloy that serve as stable and efficient catalyst for selective glucose electrooxidation to potassium gluconate at high current density. AuCu alloy ensures the co-adsorption of OH⁻ on electron-deficient Cu^δ+ sites and glucose on electron-rich Au^δ− sites, stimulating the formation of oxidative *OH and intermediates. Selective adsorption of OH species on Cu^δ+ sites also restrains the Au-OH formation and its subsequent oxidation to AuO_x, thereby preventing catalyst deactivation. Especially, for glucose electrooxidation, Au₄Cu₂ alloy delivers a high selectivity toward potassium gluconate (97.15%), along with a low potential of 0.74 V (versus reversible hydrogen electrode) to achieve industrial current density of 500 mA cm⁻². Furthermore, Au₄Cu₂ alloy realizes a stable electrolysis with a potassium gluconate productivity of 9.46 mmol cm^–2 h^–1 and Faraday efficiency of 93.60% in the membrane-free flow electrolyzer.</p>