Arsenic contamination in groundwater poses a critical threat to public health, particularly in developing regions. This study investigates the potential of KMnO₄-modified laterite as a cost-effective and efficient adsorbent for arsenic removal from aqueous solutions. A series of batch adsorption experiments were conducted using synthetic arsenic-contaminated water (100 ppb), with the influence of three key operational parameters—adsorbent dosage, solution pH, and reaction time systematically analyzed through a Box–Behnken Design within the Response Surface Methodology framework. The statistical model demonstrated high predictive accuracy (R² = 0.98), and analysis of variance confirmed dosage and reaction time as significant factors, while pH had a negligible effect within the tested range. Optimal conditions for maximum arsenic removal (96.83% actual, 98.37% predicted) were determined to be a dosage of 0.97 g, pH of 3.6, and reaction time of 51 minutes. The results confirm that KMnO₄-modified laterite is a promising material for arsenic remediation, offering a sustainable and scalable solution. However, further studies are recommended to evaluate its long-term performance, regeneration potential, and effectiveness in real water systems containing multiple contaminants