In this research, zinc (II)‐substituted Keggin‐type polyoxometalate [(C₄H₉)₄N] PZnW₁₁O₃₉ (PZnW₁₁) was prepared and stabilized on the modified graphene oxide (m‐GO) for removal of methyl red (MR) dye from aqueous solution. The maximum dye degradation and significance of variables on the decolorization system in static conditions were determined using response surface methodology (RSM). The main variables affecting the decolorization performance on dye decolorization, including system temperature (25–40°C), catalyst amount (0.001–0.005 g), and irradiation time (5–25 min), were evaluated. The optimum temperature, catalyst applying amount, and irradiation time were identified as 35°C, 0.003 g, and 20 min, respectively, and the experimental dye removal value was 96.8%. The high regression coefficient between the response and the variables (R² = 0.9335) showed a good investigation of the experimental results by regression‐based polynomial model. In comparison with the previously reported photocatalytic decolorization systems, the dye removal system suggested in this work is quick, easy and involves a small amount of catalyst. Polyoxometalate‐based photocatalyst (PZnW₁₁/m‐GO) shows potent visible‐light photocatalytic activity for the decolorization of methyl red dye, due to the generates the strong oxidants hydroxyl radical (OH) and superoxide anion radical (O₂⁻) via photoelectrochemical decomposition of H₂O and O₂ in the presence of visible light irradiation. Efficient decolorization and degradation of organic contaminants by synthesized catalyst PZnW₁₁/m‐GO suggest its potential for real industrial applications in removal of synthetic dye wastewater.