Well-defined polymers derived from biomass feedstock (e.g., soybean oil, rosin acid, and furfural) were successfully prepared by metal-free atom transfer radical polymerization (ATRP). In the presence of photoredox catalysts and UV irradiation, three biomass-based methacrylate monomers were efficiently polymerized with good control over molecular weight and dispersity. NMR. and MALDI-TOF MS confirmed high fidelity of chain end groups originated from initiators. Furthermore, block copolymers from these monomers were also achieved through chain extension by metal-free ATRP.