In this work, the electrochemical CO2 reduction reaction (CO2RR) over transition metal and α-In2Se3 monolayer catalysts was investigated by density functional theory (DFT) and an effective screening medium method-reference interaction site model (ESM-RISM). On the basis of the scaling relationship between the adsorption free energies of intermediates, we constructed the relationships between oxygen-bound intermediates with *O and carbon-bound intermediates with *CHO. The calculation results indicate that *OCHO intermediates are more favorable for the first hydrogenation of CO2 on M@In2Se3 catalysts; thus, the adsorption energy of oxygen-bound species determines the catalytic performance of M@In2Se3. The Co@In2Se3↓-C was predicted to be the most promising catalyst with a low limiting potential of -0.385 V as determined by the computational hydrogen electrode method. Constant potential calculations also demonstrate that the M@In2Se3 catalysts hold great potential for highly efficient CO2RR. This work provides a fundamental understanding for the rational design of ferroelectric single-atom catalysts for the purpose of highly efficient electrocatalytic CO2 reduction.