Controlled radical polymerizations have significantly impacted the field of polymer science by facilitating the synthesis of polymers with greater control over molecular weight, structure, and dispersity (D). As these synthetic techniques continue to evolve, more degrees of control can be realized via external regulation. Recent work has demonstrated external regulation of a controlled radical polymerization process with light using a photoredox Ir-catalyst. While light offers many advantages as a stimulus for polymerization, scaling up presents unique challenges such as shallow and uneven penetration of light through the reaction medium, which negatively impacts the rate of polymerization. This work addresses some of the challenges associated with scaling up light-mediated controlled radical polymerizations by employing a continuous flow microreactor and selecting appropriate reactor materials for oxygen sensitive reactions. (c) 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 2693-2698