Dyes are a prominent category of organic pollutants that have adverse effects on both human health and aquatic ecosystems. Adsorbents that are generated from agriculture, particularly those that are used for adsorption, have garnered an increasing amount of interest in the textile industry. In this experiment, methylene blue (MB) was removed from a liquid using a coconut shell. The accessibility and cost-effectiveness of these materials contribute significantly to their role as a major expense in batch studies for wastewater treatment. RSM determines the independent variables using a face-centered central composite design. The ability of biomass coconut shells to adsorb colors from liquid solutions, such as methylene blue, was assessed using RSM. An optimal result of 94.70% dye removal was achieved using specific parameters: a dye concentration of 30 mg/L, 1.5 mg of biomass, an initial pH of 7, a contact time of 60 min, and a temperature of 25 °C. Based on scientific analysis, it has been concluded that coconut shell biomass is a highly efficient biosorbent for removing methylene blue from wastewater effluents. Moreover, this biosorbent shows great potential in terms of being biodegradable, environmentally friendly, cost-effective, and economically feasible.