As a critical alternative step for the synthesis of important chemical feedstocks and complex carbon-based fuels, the electrochemical transformation of CO2 into CO holds great significance for the chemical industry. Here, MnO2 nanosheets array supported nickel foam has been synthesized and adopted as a binder-free catalyst for electrochemical CO2 reduction reaction (CO2RR). The well-distributed nanosheets of MnO2 impart a much higher density of accessible active sites for CO2RR, enabling the selective CO2 reduction to CO with a large current density (14.1 mA cm-2), excellent Faradaic efficiency (71%) and high electrochemical stability (10 h). This work first demonstrates the great potential of Mn-based oxides for electrocatalytic transformation of CO2 to valuable products.