Dual-atom catalysts (DACs) have emerged as efficient electrocatalysts for CO reduction owing to the synergistic effect between the binary metal sites. However, rationally modulating the electronic structure of DACs to optimize the catalytic performance remains a great challenge. Herein, we report the electronic structure modulation of three Ni DACs (namely, Ni -N , Ni -N C and Ni -N C ) by the regulation of the coordination environments around the dual-atom Ni centres. As a result, Ni -N C exhibits significantly improved electrocatalytic activity for CO reduction, not only better than the corresponding single-atom Ni catalyst (Ni-N C ), but also higher than Ni -N and Ni -N C DACs. Density functional theory (DFT) calculations revealed that the high electrocatalytic activity of Ni -N C for CO reduction could be attributed to the electronic structure modulation to the Ni centre and the resulted proper binding energies to COOH* and CO* intermediates.