Industrial effluents containing synthetic dyes represent one of the major sources of environmental pollution due to their high chemical stability, toxicity, and resistance toward natural biodegradation processes. Among numerous synthetic dyes, Metanil Yellow and Indigo Carmine are widely used in textile, cosmetic, leather, paper, and food industries. Their discharge into aquatic environments results in serious ecological and health concerns including inhibition of photosynthetic activity, reduction in dissolved oxygen concentration, mutagenicity, and carcinogenic effects. Conventional wastewater treatment methods often fail to completely remove these persistent dyes due to their complex molecular structures. The present investigation aims to perform a comparative study on the photocatalytic degradation of Metanil Yellow and Indigo Carmine using Dowex 1×4 resin-supported photocatalytic systems under controlled experimental conditions. The effects of operational parameters including initial dye concentration, catalyst loading, pH, and light intensity were systematically examined. The photocatalytic process was monitored through UV–Visible spectrophotometric analysis. Experimental observations indicated that both dyes undergo effective degradation under irradiation conditions; however, Indigo Carmine exhibited relatively faster degradation than Metanil Yellow under identical experimental conditions. Increasing catalyst loading improved degradation efficiency, whereas increasing dye concentration reduced degradation performance. Alkaline conditions enhanced degradation due to increased hydroxyl radical generation. Kinetic studies confirmed pseudo-first-order reaction behavior according to the Langmuir–Hinshelwood kinetic model. The results suggest that Dowex resin-supported photocatalytic systems represent environmentally sustainable and efficient technologies for treatment of industrial dye wastewater.