Redox-responsive core cross-linked polymeric micelles were prepared by using azide-alkyne click chemistry. Poly(ethylene oxide)-b-poly(glycidyl methacrylate) (PEO-b-PGMA) copolymers were prepared by the atom transfer radical polymerization, and the PGMA parts were subsequently functionalized with azido groups. The micelles of azido-functional PEO5k-b-PGMA(1.1k)-N-3 were cross-linked using dipropargyl 3,3-dithiodipropionate as a disulfide-containing cross-linking agent. The block copolymers and polymeric micelles were characterized by using GPC, FT-IR, H-1 NMR, TEM, and DLS analyses. The nanoparticle micelles showed much improved structural stability under physiological condition, while they were rapidly dissociated in the 1,4-dithio-D,L-threitol reducing environment.