In this work, a general colloid synthesis method for CeO₂–Al₂O₃, CeO₂–SiO₂, and CeO₂–TiO₂ core-shell spheres was reported. The properties of these CeO₂-based composites were greatly dependent on the additive species. A diffusion-controlled kinetic model was applied to explore the morphology and crystallinity evolution of these core-shell spheres. CeO₂–Al₂O₃ spheres undergo a significant morphology evolution when the Ce/Al molar ratio is varied from 1 : 0.2 to 1 : 1. It also provided an effective way to observe the diffusion channel for mass transport in the diffusion process by dissolving the Al₂O₃ in CeO₂–Al₂O₃ spheres in alkaline solution. Moreover, a significant composition and structure dependent nature was observed from the UV-vis absorption spectra of these CeO₂–Al₂O₃, CeO₂–SiO₂, and CeO₂–TiO₂ core-shell spheres.