The gap between water supply and water demands is increasing day by day. With rapid increase in global population, the utilization of water is also increased which also result into wastewater generation. Among others, domestic wastewater contribute majorly in this waste generation. Grey water in domestic wastewater can be a potential source of water pollution if not be treated. Source of grey water is usually residential zone areas which includes laundry effluents, kitchen wastes etc. It was estimated that in a day if laundry industry washes 1 kg clothes it will consume 15 L water and will produce 400m3 of wastewater, which includes contaminants such as heavy metals, organic contaminants etc. As a result, even at small concentrations, these pollutants are irresistibly pushed into our food chain. So, heavy metals should be removed from the WW through appropriate method. Different treatment methods have been recognized but adsorption is more effective due to its high performance and no by product. This study aimed to develop an eco-friendly adsorbent with high adsorption potential for removing heavy metals from laundry wastewater. Activated carbon (AC) was synthesized from Cassia fistula seeds using 40% H₃PO₄. The adsorption was performed using batch experiments, optimizing various operating parameters, including adsorbent dose (g/mL), pH, contact time (hours), and temperature (℃).Several tests were conducted on the activated carbon (AC), including moisture content, volatile matter, ash content, and fixed carbon. Characterization of the AC was performed using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Various parameters, including pH, EC, COD, and TDS, of the laundry wastewater were measured before and after treatment at different pH levels and adsorbent dosages (g/mL).The experiments were conducted to evaluate the efficiency of the adsorbent in achieving maximum removal of heavy metals such as Pb, Zn, Ni, and Cu from wastewater. The activated carbon derived from Cassia fistula showed removal efficiencies of 96% for Pb, 95% for Cr, 94% for As, 93% for Ni, 92% for Cu, 90% for Zn and 90% for Cd. The treated wastewater was further analyzed for its effect on wheat seed germination.