A　visible　light-regulated　organocatalytic　ring-opening　polymerization　of　lactones　has　been　developed　by　harnessing　the　excited　state　acidity　of　aromatic　alcohol　photocatalysts.　Commercially　available　1-hydroxypyrene　(PyOH)　is　identified　as　an　efficient　organic　photocatalyst,　which　afforded　excellent　control　on　the　polymerization,　a　reversible　activity　mediation　by　light,　and　the　well-defined　polyester　products　with　predictable　molecule　mass　and　narrow　dispersity.　©　The　Royal　Society　of　Chemistry.