The use of a tripodal Schiff base, tris[N-(2-(4-(dimethylamino)pyridylmethyl)-2-iminoethyl]amine (PyNMe23Tren), as a highly active claw-type ligand for photo-induced atom transfer radical polymerization (Photo-ATRP) is reported. CuBr2 / PyNMe23Tren is employed as the catalyst for Photo-ATRP of styrene (St) under the irradiation of visible or ultraviolet light. Well-defined polystyrene (PSt) could be synthesized with high chain-end functionality confirmed by in situ chain extension and PSt-Br macroinitiator for the secondary polymerization of St. Through switching the light “on” and “off”, temporal control of Photo-ATRP was successfully demonstrated. After the polymerization, the reaction system appeared stratification and the upper layer PSt could be facilely separated from the system.