Facile synthesis of efficient electrocatalysts that can selectively convert CO₂ to value-added chemicals remains a challenge. Herein, the electrochemical synthesis of porous Bi dendrite electrodes and details of their activity toward CO₂ conversion to formate in aqueous solutions of bicarbonate are presented. The as-synthesized multilayered, porous, dendritic Bi electrodes exhibit a faradaic efficiency (FE) of approximately 100% for formate production. Added halides and cations significantly influence the steady-state partial current density for formate production JFM (Cl^-＞Br^-＞□I^-; Cs⁺＞K⁺＞Li⁺). Photovoltaiccell- assisted electrocatalysis produced formate with an FE of approximately 95% (JFM□10 mA cm^-2) at an overall solar conversion efficiency of approximately 8.5%. The Bi electrodes maintain their activity for 360 h without a change in the surface states.