The controlled synthesis of smart multicomponent copolymers can afford new insight into structure-property correlations. Given the lack of CO2 and O2 dual-gas-responsive star polymers, this study is focused on the facile synthesis and properties of multiresponsive ABC star quaterpolymers. The “core-first” strategy was adopted to generate P(ATL-co-NIPAM)-arm-PCL-arm-PDPA stars, followed by tandem amine-thiol-ene conjugation to construct the desired stars bearing O2-/oxidation-responsive and hydrogen bond-switchable Y junctions. Upon composition change, pH switching, gas bubbling and oxidation, the copolymer solution tended to show different cloud points. Furthermore, the sizes and morphologies of copolymer assemblies were strongly dependent on chemical composition and thermal, pH, CO2, O2 and oxidative stimuli, and abundant morphologies such as large compound micelles, hyperbranched micelles, disk-like micelles, spindle-like micelles, ellipsoidal micelles, and multicompartment vesicles could be formed under distinct conditions. Our study affords a promising yet straightforward approach to construct multicomponent miktoarm star polymer, and the composition-/stimuli-dependent thermoresponsive and aggregation behaviors of these polymers pave the way for multipurpose applications. By virtue of “core first” method, ABC star quaterpolymers were controllably synthesized by combination of controlled polymerization and thiolactone chemistry. The miktoarm stars were responsive to temperature, pH, CO2, O2 and oxidation, and thus the phase transition temperature, size and morphology of copolymer assemblies could be efficiently tuned via adopting a single stimulus or combined stimuli.