Copper‐modified ceria catalysts, (CuO)x/Ce0.9Cu0.1O2 nanospheres, for low‐temperature CO oxidation were fabricated simply by using the hydrothermal synthesis of Cu‐doped CeO2 (Ce0.9Cu0.1O2) nanospheres followed by deposition of CuO over Ce0.9Cu0.1O2. The X‐ray diffraction and electron spectroscopy characterizations demonstrated that the as‐prepared nanospheres were composed of cubic CeO2 and monoclinic CuO with a typical diameter of around 70 nm. Moreover, the X‐ray photoelectron spectroscopy (XPS) analysis illustrated the coexistence of Ce4+/Ce3+ and Cu2+/Cu+ redox couples in (CuO)x/Ce0.9Cu0.1O2 and H2 temperature‐programmed reduction (TPR) measurements indicated the excellent reduction behavior of the catalyst. The Raman spectra illustrated the oxygen vacancy in (CuO)0.3/Ce0.9Cu0.1O2, and diffuse‐reflectance infrared Fourier transform spectroscopy (DRIFTS) demonstrated the stable existence of Cu+ species during CO oxidation. The (CuO)x/Ce0.9Cu0.1O2 nanospheres showed excellent catalytic activity toward CO oxidation in normal feed gas (volume ratio of CO/O2/N2=1:10:89) at ambient temperature. Catalytic tests revealed that the proportion of CuO in the final product has a strong influence on the resultant catalytic activities. The (CuO)x/Ce0.9Cu0.1O2 nanospheres hold great application potential as new catalysts for CO oxidation.