The　covalent　organic　framework　(COF)　has　been　investigated　as　an　ideal　platform　for　heterogeneous　photocatalysis,　as　it　can　integrate　large　π-conjugated　systems　and　customize　ligand　structure　to　adjust　electron　distribution　and　efficiently　promote　photoelectric　conversion.　Herein,　TAPT-DMTA-COF　and　TAPT-DMTA/TP-COF　were　designed　and　investigated　as　metal-free　reactive　oxygen　species　(ROS)　generators　to　facilitate　generation　of　ROS　clusters　to　initiate　reversible　addition-fragmentation　chain　transfer　(RAFT)　polymerization　(ROS-RAFT)　in　open　vessels　under　aqueous　conditions,　yielding　polymers　with　acceptable　molecular　weights　and　narrow　values　for　dispersity.　Chain-extension　and　light-control　experiments　demonstrated　the　high　chain-end　fidelity　of　the　polymers　and　the　light-dependent　features　of　the　polymerization　process.　Electron　donor　group　(-OMe)-modulated　TAPT-DMTA/TP-COF　can　efficiently　improve　the　ability　of　TAPT-TP-COF　to　produce　ROS　and　accelerate　ROS-RAFT　polymerization.　This　work　provides　a　new　method　for　constructing　ROS-RAFT　polymerization　photocatalysts　by　adjusting　the　ligand　structure　of　the　COF,　and　establishes　a　controlled　polymerization　methodology　for　expanding　the　applications　of　RAFT　polymerization.　©　2023　The　Royal　Society　of　Chemistry.