Electrochemical conversion of CO2 into methanol has received extensive attention in recent years since methanol is an efficient energy carrier and industrial feedstock. However, the selectivity to methanol remains unsatisfied. In this work, Sb-doped Cs3Cu2I5 is first and rationally developed for CO2 electrochemical reduction, achieving remarkable high selectivity of methanol. UV-vis absorption, X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) calculations show that the Sb dopants narrow the band gap of Cs3Cu2I5 and enhance the metal-ligand hybridization due to the introduction of Sb 5p orbitals, which accordingly enhance the charge transfer. In addition, the Cu-Sb pair in Sb@Cs3Cu2I5 perovskite synergistically catalyzes the CO2 conversion. The Cu sites serve for CO2 absorption and activation, while the Sb sites stabilize the intermediate *OCH2 through the Sb-O bond due to superior oxygen affinity. The plasma-treated sample with electron-deficient Sb exhibits the best methanol selectivity as high as 88.38%. This work provides new insight into highly efficient metal halide perovskite-based catalysts for CO2 electrochemical conversion.