Reactions involving an alkyl radical generated from a primary alcohol by photochemistry are rare and challenging. Herein, we present a photocatalyst- and metal-free approach that enables the generation of an alkyl radical from the corresponding alcohol and the subsequent C(sp3)-C(sp3) bond formation with activated olefin, via an alkyl thianthrenium salt/Hantzsch ester electron donor-acceptor complex. This protocol for the conversion of a C-OH bond to a C-C bond is highly functionality tolerant and can successfully be used in late-stage functionalization of pharmaceuticals.