The electrochemical reduction of carbon dioxide (CO2) at room temperature into industrial chemicals and energy products offers a promising strategy to mitigate atmospheric greenhouse gas emissions. In this study, bismuthene was employed as a catalyst for CO2 reduction reaction (CO2RR). Through first-principles calculations, we evaluated the CO2RR catalytic activities of bismuth (Bi) on the (001) and (012) surfaces, analyzing the mechanisms underlying these activities. Surface energy calculations for monolayer and multilayer bismuthene confirmed that monolayer bismuthene is stable and suitable for catalytic applications. Adsorption free energies of intermediates showed that formic acid is the primary product. Furthermore, it is found that the Bi(012) surface has a lower free energy barrier than Bi(001) in the CO2RR process, representing the higher catalytic activity. These results provide theoretical insights for designing bismuthene-based CO2RR catalysts with reduced overpotential, improved efficiency and enhanced selectivity, particularly enhancing catalyst selectivity.