Polymer particles with precisely controlled shapes and internal architectures have garnered significant attention owing to their unique physical properties and diverse potential applications. In this study, we present a systematic investigation of the morphological evolution of polystyrene-block-poly(4-vinyl pyridine) (PS-b-P4VP) assemblies under three-dimensional (3D) confinement, induced by n-butanol through hydrogen bonding interactions with 4VP units. The selective localization of n-butanol within the P4VP domains leads to an expansion of its volume fraction and a substantial alteration in the hydrophilicity of the P4VP block. Consequently, these PS-b-P4VP self-assemble into particles with onion-like structure or spherical internal structure. Notably, the synergistic co-assembly of gold nanoparticles (AuNPs) with PS-b-P4VP yields core-shell-corona hybrid spheres and hybrid onion-like nanoparticles, which exhibit remarkable potential for applications in advanced sensing technologies, heterogeneous catalysis, and targeted drug delivery systems.