Abstract: Catalytic oxidation of CO is an important strategy for eliminating low-concentration carbon monoxide pollutants, and the development of highly active non-noble-metal oxide catalysts is therefore of considerable significance. To address the insufficient low-temperature activity of LaMnO₃ for CO oxidation, a series of LaMn_1−xCu_xO₃ perovskite catalysts was prepared by the sol-gel method, and the effect of Cu doping level on their catalytic performance for CO oxidation was systematically investigated. The results show that Cu doping markedly enhances the CO oxidation activity of LaMnO₃. The catalytic activity of the series exhibits a volcano-type dependence on Cu content, among which LaMn_0.6Cu_0.4O₃ delivers the best performance, with T₅₀ and T₉₀ values of 136 and 150 °C, respectively. Characterization results indicate that the outstanding CO oxidation performance of LaMn_0.6Cu_0.4O₃ mainly originates from the Cu-Mn synergistic effect, regulation of the surface electronic structure, and the enhanced participation of surface-active oxygen and lattice oxygen. The reaction is proposed to proceed predominantly via a Mars-van Krevelen pathway. This study provides a materials basis for the development of low-cost non-noble-metal catalysts and offers experimental support for understanding the synergistic roles of active oxygen, lattice oxygen, and metal centers in CO oxidation.