Pt/CeO2 catalysts with unitary Pt species, nanoparticles, clusters or single atoms, often exhibit excellent activity and unique selectivity in many catalytic reactions benefiting from their small size, abundant unsaturated active sites, and unique electronic structure. In recent years, a tremendous number of related articles have provided great inspiration to future research and development of Pt/CeO2 catalysts. In this review, the state-of-the-art evolution of Pt nanoparticles to Pt single atoms on CeO2 is reviewed with the emphasis on synthetic strategies, advanced characterization techniques (allowing one to clarify the single atoms from clusters), the catalytic applications and mechanisms from the viewpoint of theoretical calculation. Finally, the critical outlooks and the challenges faced in developing the single-atom Pt/CeO2 catalysts are highlighted.