Herein, a direct, metal-free, and site-selective electrochemical CÀ H carboxylation of arenes by reductive activation using CO 2 as the economic and abundant carboxylic source was reported. The electrocarboxylation was carried out in an operationally simple manner with high chemo-and regioselectivity, setting the stage for the challenging site-selective CÀ H carboxylation of unactivated (hetero)arenes. The robust nature of the electrochemical strategy was reflected by a broad scope of substrates with excellent atom economy and unique selectivity. Notably, the direct and selective CÀ H carboxylation of various challenging arenes worked well in this approach, including electron-deficient naphthalenes, pyridines, simple phenyl derivatives, and substituted quinolines. The method benefits from being externally catalyst-free, metal-free and base-free, which makes it extremely attractive for potential applications.