Polymer self-assembly has been one of the most important strategies for preparation of multicompartment micelles (MCMs). However, the traditional self-assembly techniques are constrained by limited common solvent, complex kinetic factors, low solids content, etc. Polymerization induced self-assembly (PISA) is a novel technique for preparation of polymer assemblies at high solids content and has been exploited to produce MCMs. Nevertheless, the morphology evolution of the MCMs obtained through PISA has not yet been well understood. Herein, we study the compartmentalization behaviors of a series of MCMs constituted by poly(N,N-dimethylaminoethyl methacrylate)-b-poly(benzyl methacrylate)-b-poly(2-perfluorohexylethyl methacrylate) (PDMA-b-PBzMA-b-PFHEMA) triblock terpolymers, which were synthesized by seeded reversible addition fragmentation chain transfer (RAFT) dispersion polymerization of FHEMA using PDMA-b-PBzMA micelles, wormlike micelles, or vesicles as the seeds. Because of the strong incompatibility between PBzMA and PFHEMA, MCMs with abundant compartmentalized nanostructures were produced. Phosphotungstic acid- and RuO4-stained TEM images of these MCMs indicate that their morphologies are controlled by both the DPs of PBzMA and PFHEMA. Our results suggest that PISA could serve as a reliable platform for revealing the compartmentalization behaviors of polymeric assemblies.