Photocatalytic remediation using semiconductor nanoparticles presents a promising approach for water purification. In this study, cadmium sulfide (CdS) nanoparticles were synthesized via a plant-mediated approach and evaluated for their efficacy in removing Cr(VI) and Rhodamine B contaminants from aqueous solutions under visible light irradiation. The CdS nanoparticles were characterized by X-ray diffraction (XRD), which confirmed the presence of the cubic phase with a crystallite size of 10 nm. UV–visible diffuse reflectance spectroscopy (DRS) indicated bandgap energy of 2.4 eV, facilitating visible light absorption. Photoluminescence (PL) spectroscopy revealed reduced recombination rates of photogenerated charge carriers, enhancing photocatalytic efficiency. The synthesized CdS nanoparticles demonstrated efficient removal of both Cr(VI) and Rhodamine B, achieving degradation efficiencies of 92 % and 95 %, respectively, within 120 min under optimized conditions. Mechanistic insights suggest the generation of reactive oxygen species (ROS) and electron-hole pairs (e-/h+) contributing to pollutant degradation. This study underscores the potential of plant-mediated CdS nanoparticles as effective photocatalysts for environmental remediation applications.