<p>The discharge of dye-containing wastewater poses a significant environmental challenge due to the persistence, toxicity, and low biodegradability of many synthetic dyes. Advanced Oxidation Processes (AOPs) have emerged as effective treatment technologies for generating highly reactive oxidizing species that degrade recalcitrant organic contaminants. Traditionally, dye degradation in AOPs has been attributed to radical pathways involving hydroxyl (⋅OH) and sulfate (SO₄⋅⁻) radicals, which exhibit high oxidation potentials and rapid reaction kinetics. More recently, non-radical pathways, including singlet oxygen (¹O₂), high-valent metal species, and surface-mediated electron transfer, have attracted increasing attention owing to their enhanced selectivity, reduced matrix interference, and improved oxidant utilization. This comprehensive review critically compares radical and non-radical oxidation mechanisms for dye removal, highlighting how the dye's ionic character, molecular structure, catalyst properties, and operating conditions influence degradation behavior and the dominance of degradation pathways. Particular emphasis is placed on the interactions among adsorption processes, reactive oxygen species generation, and electron-transfer reactions that govern oxidation efficiency and selectivity. Furthermore, current challenges in mechanistic identification, catalyst design, and process optimization are discussed. By integrating recent advances in catalytic activation strategies and mechanistic investigations, this review provides a unified framework for understanding the evolution of oxidation pathways and offers perspectives on the development of selective, energy-efficient, and sustainable AOP technologies for the treatment of dye-contaminated wastewater.</p> Graphical Abstract <p></p>