Here we report a partially oxidized palladium nanodot (Pd/PdOx) catalyst with a diameter of around 4.5 nm. In aqueous CO2‐saturated 0.5 m KHCO3, the catalyst displays a Faradaic efficiency (FE) of 90 % at −0.55 V vs. reversible hydrogen electrode (RHE) for carbon monoxide (CO) production, and the activity can be retained for at least 24 h. The improved catalytic activity can be attributed to the strong adsorption of CO2.− intermediate on the Pd/PdOx electrode, wherein the presence of Pd2+ during the electroreduction reaction of CO2 may play an important role in accelerating the carbon dioxide reduction reaction (CO2RR). This study explores the catalytic mechanism of a partially oxidized nanostructured Pd electrocatalyst and provides new opportunities for improving the CO2RR performance of metal systems.