This study focuses on the catalytic wet peroxide oxidation (CWPO) of the synthetic azo dye Methyl Orange (MO) using a set of clay-based catalysts impregnated with transition metals (Cu, V, Fe, and Mn). The prepared materials Cu/Clay, V/Clay, Fe/Clay, and Mn/Clay–were obtained through a wet impregnation route and characterized in detail using X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FTIR) to elucidate their structural and surface properties. The degradation of MO was investigated under exclusive experimental conditions, including variations in catalyst loading, hydrogen peroxide concentration, and pH. Kinetic information indicated that the oxidation followed a pseudo–first order reaction. Among the examined catalysts, Cu/Clay exhibited the most efficient oxidative conduct, achieving approximately 98% color removal and nearly 70% reduction in chemical oxygen demand (COD) reduction after 3 h under optimized conditions (5% Cu loading, 4  g L⁻¹ catalyst). The catalytic activity decreased in the following order: Cu/Clay > V/Clay > Mn/Clay > Fe/Clay. Overall, these effects suggest that copper-modified clays can function as sensible, low-cost, and environmentally sustainable catalysts for advanced oxidation processes (AOPs) to treat dye-contaminated wastewater.