A water-controlled regioselective phosphinoylation of enamines with H-phosphine oxides has been established through Lewis ac-id-mediated C-N bond cleavage in this work, which provides a novel strategy for accessing various geminal and vicinal phosphinoyl products 3a, 4a and 5a in high yields. The transformation features excellent functional group tolerance, operational simplicity, and high atom economy, and is amenable for phosphinoylation of complex molecule skeletons. Preliminary mechanism studies suggest the conversion from 3a to 4a and 5a involve the elimination of hydroxyl group, and water molecules play a critical role in influencing the reaction pathway and product selectivity. This research provides significant value to regioselective functionalization of enami-nones.