Ag@CeO₂ core–shell nanospheres were synthesized by a facile one-step solvothermal route from Ce(NO₃)₃·6H₂O, AgNO₃, poly(N-vinylpyrrolidone) (PVP), and ethanol. The structure, composition, BET specific surface area and optical properties of Ag@CeO₂ core–shell nanospheres were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, high resolution transmission electron microscopy, N₂ adsorption–desorption isotherm analysis, and UV-vis diffuse reflectance spectroscopy. Field emission scanning, high resolution transmission electron microscopy and X-ray photoelectron spectroscopy etching results of the as-synthesized Ag@CeO₂ nanospheres revealed that the as-synthesized Ag@CeO₂ nanospheres consist of a Ag core and a CeO₂ shell. The catalytic results demonstrated that the as-synthesized Ag@CeO₂ nanospheres possessed higher catalytic activity than pure Ag (which was synthesized by a similar solvothermal method) in the reduction of 4-nitrophenol. Their enhanced catalytic activity is found to be due to the unique oxidized Ag species induced by the strong interaction between the core surface of Ag nanospheres and surface defects (oxygen vacancies) of the CeO₂ shell. The herein proposed Ag@CeO₂ core–shell nanospheres are promising catalytic candidates for the reduction of p-nitrophenol because of their simple preparation route and high catalytic activity.