The growing environmental threat posed by macro- and microplastics has intensified the search for sustainable degradation methods. Photocatalysis, using titanium dioxide (TiO₂) as a catalyst, has emerged as an efficient and eco-friendly approach to breaking down plastic waste. Under ultraviolet (UV) or visible light irradiation, TiO₂ generates reactive oxygen species (ROS) that oxidize polymer chains, converting plastics into smaller, less harmful by-products such as carbon dioxide, water, and organic intermediates. This process is effective for degrading various plastic types, including polyethylene, polypropylene, and polystyrene, at both macro and micro scales. Recent advancements have focused on enhancing TiO₂ photocatalytic efficiency through doping with metals or non-metals and combining it with other semiconductors to expand light absorption into the visible spectrum. Furthermore, the integration of TiO₂ into composite systems has improved its stability and recyclability, making it more suitable for large-scale applications. Despite its potential, challenges such as slow degradation rates, the formation of secondary pollutants, and limited efficiency under natural sunlight remain. This chapter will explores the principles, applications, and advancements in TiO₂-mediated photocatalytic degradation of plastics, highlighting its role in addressing plastic pollution and promoting sustainable environmental practices. Further research and technological innovation are necessary to optimize this method for widespread implementation.