This study presents the synthesis and characterization of ZnO/CuS hybrid nanocomposites designed for the photocatalytic degradation of methylene blue dye. The nanocomposites were synthesized using a microwave-assisted hydrothermal method, where copper sulfide (CuS) was prepared first, followed by the addition of zinc oxide nanoparticles (ZnO NPs). The successful integration of CuS and ZnO was confirmed using various characterization techniques, including X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy, and Fourier-transform infrared spectroscopy (FTIR). Optical properties were also investigated utilizing diffused reflectance spectroscopy (DRS), revealing that the band gap energy of the hybrid material (3.21 eV) was lower than that of pure ZnO (3.29 eV), indicating enhanced photocatalytic activity. Photocatalytic degradation experiments demonstrated high efficiency in decolorizing methylene blue, with complete dye degradation achieved under optimal conditions: photocatalyst dosage of 0.1 g/L, dye concentration of 10 ppm, and pH of 9. These findings highlight the potential of ZnO/CuS nanocomposites for practical applications in wastewater treatment. Furthermore, the influence of salinity, inorganic oxyanions, and scavengers on photocatalytic performance was systematically investigated, providing important insights into the operational parameters required to utilize ZnO/CuS nanocomposites in environmental remediation effectively.