In this study, a novel well-defined macromonomer of epoxy end-functionalized polystyrene was synthesized by atom transfer radical polymerization (ATRP). The compound 3-cyclohexenylmethyl-2-bromopropanoate was synthesized by the condensation of 3-cyclohexene-1-methanol with 2-bromopropanoyl bromide. Subsequently, the epoxidation of the obtained 3-cyclohexenylmethyl-2-bromopropanoate using 3-chloroperoxybenzoic acid results in a new epoxy functional ATRP initiator. The ATRP of styrene (St) in bulk at 110 °C, by means of this initiator in conjunction with the cuprous complex Cu(I)Br/bipyridine, yields a well-defined macromonomer of polystyrene with an epoxy end group. GPC, IR, and 1H NMR analyses revealed that a low-polydispersity polystyrene with the desired functionality at the end of the chain was obtained. The photoinduced cationic polymerization of this macromonomer yielded graft and block copolymers.