A simple and efficient method for the visible light induced direct carbon alkylation of quinoxalin-2(1H)-ones at the C3 position is described. This protocol employs cheap and readily available phenyliodine(iii) dicarboxylates as the alkylation reagents to conduct decarboxylative radical coupling reaction with quinoxalin-2(1H)-ones. The process exhibits excellent compatibility to functional groups and provides a convenient and selective access to various 3-alkylquinoxalin-2(1H)-ones in good yields.