Continuous-flow chemistry represents a robust setting for photochemical reactions. We have developed the first computer-aided droplet-flow platform for photocontrolled radical polymerization. This method allows precise and scalable living polymerizations of monomers at high concentrations in flow, even when solids are generated. The consistent good performance of polymerization during the programmed change of reaction conditions demonstrates the reliability and utility of this method. Furthermore, the droplet-flow approach not only streamlines an automated high- throughput living polymerization (275 droplets of samples in 11 min), which enables the rapid generation of copolymer libraries for low-cost structure-property relationship screening, but also allows on-line switching to desirable reaction conditions for the scale-up (co)polymerization purpose.