The carbon dioxide (CO2) capture and utilization has attracted a great attention in organic synthesis. Herein, an unpresented transient stabilization effect (TSE) of CO2 is disclosed and well applied to the electrochemical hydrogenation of azo compounds to hydrazine derivatives. Mechanistic experiments and computational studies imply that CO2 can capture azo radical anion intermediates to protect the hydrogenation from potential degradation reactions, and is finally released through decarboxylation. The promotion effect of CO2 was further demonstrated to work in the preliminary study of electrochemical reductive coupling of α‐ketoesters to vicinal diol derivatives. For the electrochemical reductive reactions mentioned above, CO2 is indispensable. The presented results shed light on a different usage of CO2 and could inspire novel experimental design by using CO2 as a transient protecting group. A new transient stabilization effect (TSE) of CO2 is identified and applied to the electrochemical hydrogenation of azo compounds and the reductive coupling of α‐ketoesters. The TSE influence of CO2 means that overactive intermediates can be captured by CO2 to prevent their decomposition or side reaction to complete the synthesis that is difficult to achieve by direct means. The CO2 can be released later through a decarboxylation process.