AbstractIn general, commercial ZnO owns the poor selectivity and activity toward electroreduction CO₂ to formate. In contrast, the numbers of Sn‐based nanomaterials are reported as excellent electrocatalysts for formate production, however, the metallic Sn is more expensive than Zn. In this study, it is demonstrated that an atomically dispersed Sn on a tensile‐strained ZnO nanosheet (Sn SA/ZnO) shows dramatically improved activity and selectivity for formate production over a wide potential window compared with that of commercial ZnO. Especially, Sn SA/ZnO exhibits 205‐fold mass activity enhancement than the commercial Sn at −1.7 V versus reversible hydrogen electrode normalized with element Sn. The experimental measurements combined with theoretical calculations revealed that Sn SA/ZnO can effectively capture and activate CO₂ by its exposed double‐active sites (Sn and O), while the tensile strain on its surface boosts the catalytic selectivity by strengthening the adsorption of the *HCOO intermediate for the electrochemical reduction of CO₂ to formate.