The carbon dioxide electroreduction reaction (CO₂RR) to fuels and/or chemicals is an efficient prospective strategy to realize global carbon management using intermittent electric energy harvested from renewable sources. Highly efficient inexpensive electrocatalysts are required to achieve high energy and Faradaic efficiencies as well as fast conversion. Metal–nitrogen–carbon (M–N–C) single-site catalysts (SSCs) are highly competitive over precious metal catalysts in the CO₂RR to CO due to their high performance, easy regulation and low cost. In the past six years, intensive studies of M–N–C SSCs for CO₂RR to CO have been performed, and great progress has been achieved. This review focuses on the important topic of CO₂RR to CO with M–N–C SSCs. We first introduce the reaction mechanism of the CO₂RR to CO and the regulation of the electronic structure from a theoretical viewpoint. Then, the construction of M–N–C SSCs and the regulation of the electronic structure are demonstrated experimentally. The up-to-date electrocatalytic performance of M–N–C SSCs with different metal centers (Ni, Fe, Co and others) is summarized and compared systematically to highlight structure–performance correlations that were considered from both theoretical and experimental perspectives. Finally, the opportunities, challenges and future outlooks are summarized to deepen and widen research and applications in this promising field.