Developing efficient and stable non-noble metal catalysts for the catalytic oxidation of volatile organic compounds (VOCs) has always been key for controlling air pollution. For this, cerium dioxide (CeO₂) is a potential material and its morphology has a significant impact on the catalyst performance. Herein, three types of CeO₂ with different morphologies were prepared using the hard template method and successfully applied to toluene oxidation. The CeO₂ nanoparticles catalyst (CeO₂-NP) exhibited the highest efficiency, excellent water resistance, long-term stability, and cycle regeneration. Notably, the activation and migration of lattice oxygen can be facilitated by increasing the temperature, and the oxygen vacancies on the surface of the catalyst can further promote the process. In addition, the oxidation behavior of toluene over the CeO₂-NP catalyst was comprehensively understood by in situ diffuse reflectance infrared Fourier transform spectroscopy (In situ DRIFTS) combined with density functional theory (DFT). It was found that the ring-opening reaction is an essential rate-controlling step. Thus, this study provides a new strategy for exploring mono-metal catalysts with high catalytic performances for the oxidation of VOCs and other pollutants.