Isoquinoline alkaloids are attractive natural products due to their diverse chemical structures as well as remarkable bioactivities. Herein, we report the concise total syntheses of two isoquinoline alkaloids, menisporphine and daurioxoisoporphine C, through a mild and efficient photoredox-catalyzed direct C-H arylation of isoquinoline core with aryldiazonium salt. This new strategy is complementary to the conventional isoquinoline synthesis and would provide us a useful means to achieve a more convergent and flexible approach to access diverse isoquinoline structures.