A composite nanofiltration membrane was successfully fabricated via a single-step electrospraying process for the efficient removal of bentazone from contaminated water. Key electrospraying parameters—polymer concentration, solution flow rate, and applied electric field strength—were systematically optimized using the Taguchi design of experiments, which identified polymer concentration as the most influential factor governing membrane performance. The optimum fabrication conditions were determined to be a 5 %wt polymer concentration, a 2.2 mL h⁻¹ flow rate, and a 0.66 kV cm⁻¹ electric field strength. The fabricated membranes were characterized using scanning electron microscopy, nitrogen adsorption–desorption, water contact angle, and surface profilometry. Membrane performance was evaluated using a 200 mg L⁻¹ bentazone feed solution in a vacuum-assisted dead-end filtration system operated at a transmembrane pressure of 10 psi. Under these optimal conditions, the membrane exhibited a pure water flux of 34.7 L. m⁻².h⁻¹. During bentazone filtration, the flux decreased to 19.75 L. m⁻².h⁻¹, while achieving an excellent bentazone rejection of 96.2 ± 1.44%. These findings confirm that optimizing electrospraying parameters, particularly polymer concentration, is critical for developing high-performance composite nanofiltration membranes. Overall, the proposed single-step electrospraying method offers a simple, highly controllable, and practical alternative to conventional approaches for fabricating composite nanofiltration membranes.