Developing selective and cost-effective CO₂ reduction electrocatalysts is critical for electrochemical production of carbon-containing fuels. In this communication, we report on the in situ fabrication of a bromide-derived porous Ag nanowire film (BD-Ag) with adsorbed Br⁻ anions via anodic oxidation of commerical Ag foil and subsequent electrochemical reduction. The resulting BD-Ag behaves as an efficient electrocatalyst for CO₂ reduction to CO with high selectivity, with a low onset overpotential of only 296 mV and a high CO faradaic efficiency of 96.2% in 0.5 M KHCO₃. Furthermore, it also shows excellent long-term electrochemical durability. This work offers an attractive catalyst material toward efficient and selective CO₂ reduction for electrocatalytic applications.