This research investigates the green synthesis of cadmium sulphide (CdS) nanoparticles using curry leaves (Murraya koenigii) and their application in domestic wastewater treatment. The study employs a sol-gel method to produce environmentally friendly nanoparticles, which are characterized for their size, morphology, and composition. The synthesized CdS nanoparticles were tested for their effectiveness in reducing biochemical oxygen demand (BOD) and total organic carbon (TOC) levels in wastewater samples. Results indicate a significant reduction in both BOD and TOC, demonstrating the potential of these nanoparticles in enhancing water quality. The findings support the use of green synthesis methods in nanotechnology, promoting sustainable practices in wastewater management. This study contributes to the understanding of utilizing natural materials for nanoparticle production, highlighting their biocompatibility and environmental benefits.