Abstract: Carbon dioxide resource utilization is an important approach for achieving carbon cycling, and TiO2 has been widely investigated for photocatalytic CO2 reduction owing to its high chemical stability, low cost, and environmental compatibility. However, the practical application of TiO2-based photocatalytic systems is restricted by their limited light absorption, rapid charge carrier recombination, and insufficient CO2 activation capability. This review summarizes the fundamental mechanisms of TiO2 photocatalytic CO2 reduction, including photogenerated carrier migration, CO2 adsorption and activation, and the conversion pathways of key intermediates. Recent advances in performance enhancement strategies are systematically discussed, including metal cocatalyst modification, semiconductor heterojunction construction, metal–organic framework coupling, and defect, doping, and multicomponent synergistic regulation. In addition, engineering factors affecting practical operation, such as CO2 source and concentration, mass transfer, light utilization, catalyst stability, and flue gas impurities, are analyzed, with emphasis on the development of gas–solid, gas–liquid–solid, and continuous-flow reactors. The review indicates that the improvement of TiO2-based photocatalytic CO2 reduction has gradually shifted from single material modification toward the synergistic regulation of interfacial charge transfer, active sites, and reaction processes. Nevertheless, the adaptability to complex carbon sources, long-term operational stability, and reactor scale-up remain key challenges for practical applications. Future efforts should focus on integrating precise catalyst design with reactor engineering optimization to promote the continuous and practical application of TiO2-based photocatalytic CO2 reduction technologies.