Nickel-catalyzed carboxylation of aryl and vinyl chlorides employing carbon dioxide has been developed. The reactions proceeded under a CO2 pressure of 1 atm at room temperature in the presence of nickel catalysts and Mn powder as a reducing agent. Various aryl chlorides could be converted to the corresponding carboxylic acid in good to high yields. Furthermore, vinyl chlorides were successfully carboxylated with CO2. Mechanistic study suggests that Ni(I) species is involved in the catalytic cycle.