AbstractWe explored a co‐dissolved strategy to embed mono‐dispersed Pt center into V₂O₅support via dissolving [PtV₉O₂₈]⁷⁻into [V₁₀O₂₈]⁶⁻aqueous solution. The uniform dispersion of [PtV₉O₂₈]⁷⁻in [V₁₀O₂₈]⁶⁻solution allows [PtV₉O₂₈]⁷⁻to be surrounded by [V₁₀O₂₈]⁶⁻clusters via a freeze‐drying process. The V centers in both [PtV₉O₂₈]⁷⁻and [V₁₀O₂₈]⁶⁻were converted into V₂O₅via a calcination process to stabilize Pt center. These double separations can effectively prevent the Pt center agglomeration during the high‐temperature conversion process, and achieve 100 % utilization of Pt in [PtV₉O₂₈]⁷⁻. The resulting Pt‐V₂O₅single‐atom‐site catalysts exhibit a CH₄yield of 247.6 μmol g⁻¹ h⁻¹, 25 times higher than that of Pt nanoparticle on the V₂O₅support, which was accompanied by the lactic acid photooxidation to form pyruvic acid. Systematical investigations on this unambiguous structure demonstrate an important role of Pt−O atomic pair synergy for highly efficient CO₂photoreduction.