Herein, we report a mild, rapid, straightforward method for visible-light-mediated sulfonamide ethylation to afford a diverse array of compounds with C(sp3)-sulfonamide skeletons. The method relies on inexpensive, abundant, commercially available primary, secondary, and tertiary alkyl carboxylic acids and alkyl iodides as substrates. The method has a broad substrate scope and potential utility for late-stage functionalization of natural products and synthetic medicines and can be expected to facilitate rapid structural diversification of bioactive molecules.