Monoatomic dispersion of precious metals on the surface of CeO₂ nanocrystals is a highly practical approach for dramatically reducing the usage of precious metals while exploiting the unique properties of single-atom catalysts. However, the specific atomic sites for anchoring precious metal atoms on the CeO₂ support and underlying chemical mechanism remain partially unknown. Herein, we show that the terminal hydroxyls on the (100) surface are the most stable sites for anchoring Ag atoms on CeO₂, indicating that CeO₂ nanocubes are the most efficient substrates to achieve monoatomic dispersion of Ag. Importantly, the newly identified chemical mechanism for single-metal-atom dispersion on CeO₂ nanocubes appears to be generic and can thus be extended to other precious metals (Pt and Pd). In fact, our experiments also show that atomically dispersed Pt/Pd species exhibit morphology- and temperature-dependent CO selectivity in the catalytic CO₂ hydrogenation reaction.