CeO2 is a prominent support material for heterogeneous catalysis owing to its exceptional oxygen storage capacity. CeO2 oxygen vacancy (VO) density critically influences thermal catalytic processes involving oxygen species, such as CO oxidation, CO2 hydrogenation, and volatile organic compound oxidation. This review examines recent strategies for controlling VO in CeO2, including lattice doping, nanostructure control, and defect engineering via external reduction, as well as their effects on thermal catalytic reactions. We present diverse in situ characterization techniques to elucidate the relationship between lattice oxygen mobility and catalytic reactivity during reactions. Strategies combining multiple approaches to achieve synergistic CeO2 reducibility enhancement are discussed. A comprehensive exploration of VO regulation strategies provides insights into optimizing CeO2-based systems in oxygen-mediated thermal catalysis.