Selective immobilization of single-atom Au on the specific facets of CeO₂ has been successfully performed by redox etching precipitation (REP), which makes it possible to clearly refine the interfacial effect of multiple-facet support on single atom. With systemic characterizations, it is found that single-atom Au is apt to lie on nonpolar facets of CeO₂ (111) and (110) rather than polar facet of CeO₂ (100). The modification of morphology-dependent properties is attributed to the different interaction between Au atom and each CeO₂ interface. Because of synergy between Au and CeO₂, more oxygen vacancies and more active oxygen species are generated; meanwhile, the interfacial effect stabilizes the charged Au species which serves as active site. Therefore, the performance in catalytic oxidation of HCHO and CO on CeO₂ is facilitated by loading Au. Among them, CeO₂ rod-supported Au as an optimal catalyst exhibits a remarkable activity and stability. With in-situ characterization, the reaction mechanisms for HCHO and CO oxidation over Au/r-CeO₂ are studied. Meanwhile, it is proved that REP strategy is also valid to obviously promote catalytic performance whenever commercial CeO₂ is used or Au is replaced with Ag, so the improvement of recently applied catalyst with REP process is promising.