AbstractPolymers made from isoprene and styrene resemble an important class of synthetic macromolecules found in a wide range of everyday commodity products. Their synthesis is usually limited to radical emulsion or anionic polymerization. Herein, we report on ultrafast photoiniferter reversible addition‐fragmentation chain transfer (RAFT) polymerization of isoprene and styrene in a continuous‐flow microreactor. The cooperative action of a high photoinitiation efficiency and use of elevated temperatures considerably reduces the reaction times to less than half an hour to give high monomer conversions, allowing for the first time polyisoprene to be yielded from controlled radical polymerization in high definition and reasonable reaction times. High chain‐end fidelities are maintained and block copolymers were prepared including a polystyrene‐block‐polyisoprene‐block‐polystyrene (PS‐b‐PI‐b‐PS) triblock copolymer.