Introduction of a grafted architecture into a specific block of the linear diblock copolymers produces “comb-coil” type block copolymers (CCBCP). CCBCPs having an A-b-B-g-C type architecture can be considered as a class of hybrid block copolymers that have the structural characteristics of both linear diblock copolymers and densely grafted polymers. In this study, poly(ethylene oxide)-b-poly(2-(2-bromopropionyloxy)-ethyl acrylate)-g-polystyrene (PEO-b-PBPEA-g-PS)was synthesized by combination of reversible addition-fragmentation chain transfer (RAFT) polymerization and atom transfer radical polymerization (ATRP). Use of a synthesized chain transfer agent consisting of a PEO segment in the polymerization of BPEA readily yielded a diblock copolymer consisting of initiating sties for ATRP on a specific block. Grafting of polystyrene was conducted via ATRP to produce the desired architecture. The resulting polymers were characterized by NMR, GPC, and thermal analyses. Solvent annealing of the PEO-b-PBPEA-g-PS thin film produced a vertically oriented cylindrical PEO domains in PS matrix.