An alkylation of α-C(sp 3 )-H at N -aryltetrahydroisoquinolines with alkylboronic acids was developed under visible-light irradiation in the absence of additional photocatalyst. The reaction proceeded well, tolerating a variety of functional groups, and featured low-cost and mild reaction conditions. A preliminary mechanistic study indicated that an electron donor-acceptor (EDA) complex between an electron-rich N -aryltetrahydroisoquinoline and an electron-poor alkylboronic acid was involved in the reaction.