Herein, we report a protocol for direct visible-light-mediated Minisci C–H alkylation reactions of heteroarenes with alkyl boronic acids using molecular oxygen as the sole oxidant. This mild protocol uses an inexpensive, green oxidant; permits efficient functionalization of various N-heteroarenes with a broad range of primary and secondary alkyl boronic acids; and is scalable to the gram level. We demonstrated the practicality and sustainability of the protocol by preparing or functionalizing several pharmaceuticals and natural products.