Multicompartment vesicles of ferrocene-containing triblock terpolymer containing on–off switchable pores in the vesicular membrane are prepared by seeded RAFT polymerization. In these multicompartment vesicles, the incompatible solvophobic poly(4-vinylbenzyl ferrocenecarboxylate) (PVFC) and poly(benzyl methacrylate) (PBzMA) blocks form the porous phase-segregated membrane and the solvophilic poly[2-(dimethylamino) ethyl methacrylate] block locates at the inner and outer sides of the membrane. These porous multicompartment vesicles are redox-responsive and the membrane pores can be on–off switched through redox triggering. These porous multicompartment vesicles are deemed to be new nanoassembly of ABC triblock terpolymer and are anticipated to be a smart host to load and release guests.