The electrocatalytic conversion of carbon dioxide (CO2) to formate is significant for carbon neutrality. How to improve the reaction kinetics of electrocatalysts is one of the important challenges. An innovative electrodeposition strategy is presented herein to rationally synthesize the vanadium oxide (VOx) clusters decorated Bi‐Sn alloy (BiSn(VOx)) catalyst. Theoretical and in situ spectral studies confirm the simultaneously improved kinetics of CO2 activation and subsequent protonation via VOx clusters mediated water dissociation process, thereby optimizing the electrocatalytic activity and selectivity of CO2 to formate. Remarkably, this BiSn(VOx) catalyst achieves high Faradic efficiency (FE) of formate over 90% within wide potential window of 800 mV and excellent stability over 100 h at −0.6 V versus RHE. Moreover, the BiSn(VOx) cathode integrated rechargeable Zn‐CO2 battery realizes the largest power density of 3.8 mW cm−2, while the assembled co‐electrolysis electrolyzer delivers a total FE of formate over 182% at a cell voltage of 0.6 V, outperforming the highest value so far. The work provides a promising way to develop advanced electrocatalysts for electrolysis.