The electrochemical conversion of CO2into multicarbon (C2) products on Cu-based catalysts is strongly affected by the surface coverage of adsorbed CO (*CO) intermediates and the subsequent C–C coupling. However, the increased *CO coverage inevitably leads to strong *CO repulsion and a reduced C–C coupling efficiency, thus resulting in suboptimal CO2-to-C2activity and selectivity, especially at ampere-level electrolysis current densities. Herein, we developed an atomically ordered Cu9Ga4intermetallic compound consisting of Cu square-like binding sites interspaced by catalytically inert Ga atoms. Compared to Cu(100) previously known with a high C2selectivity, the Ga-spaced, square-like Cu sites presented an elongated Cu–Cu distance that allowed to reduce *CO repulsion and increased *CO coverage simultaneously, thus endowing more efficient C–C coupling to C2products than Cu(100) and Cu(111). The Cu9Ga4catalyst exhibited an outstanding CO2-to-C2electroreduction, with a peak C2partial current density of 1207 mA cm–2and a corresponding Faradaic efficiency of 71%. Moreover, the Cu9Ga4catalyst demonstrated a high-power (∼200 W) electrolysis capability with excellent electrochemical stability.