The alarming increase in water contamination by refractory pollutants has necessitated the development of innovative and efficient treatment solutions. Advanced Oxidation Processes (AOPs) have emerged as a cutting-edge technology for effectively degrading complex organic compounds, antibiotics, pharmaceuticals, and industrial effluents through the generation of highly reactive species, such as hydroxyl radicals. This Special Issue is dedicated to exploring recent advancements in AOPs, encompassing catalytic, photocatalytic, electrochemical, and hybrid systems, as well as innovative materials and mechanistic insights. We encourage submissions that address key aspects including catalyst design, process optimization, scalability, environmental impact assessments, and cost-effectiveness. Furthermore, we welcome studies focusing on the integration of AOPs with conventional treatment methods and their practical applications in real-world scenarios. By compiling state-of-the-art research, this issue aims to promote knowledge exchange and drive the advancement of sustainable wastewater treatment strategies. Researchers are invited to submit original research articles, comprehensive reviews, and case studies to enhance the understanding and application of AOPs in addressing global water quality challenges.