In this work, we describe the use of the one-pot, photoinduced but photoinitiator-free combined copper-catalyzed azide-alkyne click cycloaddition (CuAAC) and atom-transfer radical polymerization (ATRP) protocol to provide a graft copolymer of polystyrene-g-poly(methyl methacrylate) (PS-g-PMMA) in desirable conversion and polydispersity. Poly(styrene-co-4-chloromethylstyrene) (poly(S-co-4-CMS)) was prepared using nitroxide mediated polymerization (NMP). The benzylic chloride functional groups of poly(S-co-4-CMS) were substituted for azide functional groups using a conventional azidation procedure to provide poly(styrene-co-4-azidomethylstyrene) (poly(S-co-4-AMS)). Poly(S-co-4-AMS) was then used as the backbone of the graft copolymer. The alkyne-bearing ATRP initiator propargyl 2-bromoisobutyrate (PgBiB) could then be grafted to the backbone via photoinduced CuAAC, while meanwhile initiating in tandem the poly(methyl methacrylate) (PMMA) chain growth via the ATRP mechanism. The graft polymer was provided in good conversion and polydispersity and was characterized appropriately using H-1 NMR, FT-IR and GPC.