Water pollution, driven by the discharge of dyes from industrial processes, poses a significant environmental and health hazard worldwide. Methylene blue, a common dye, constitutes particular concern due to its persistence and toxicity. Conventional wastewater treatment methods often struggle to effectively remove such contaminants. In this study, we introduce a novel approach utilizing a polysulfone-based composite membrane incorporating pretreated jute fibers and copper nanoparticles for the removal of methylene blue from aqueous solutions. The pretreated jute fibers undergo alkali and hydrogen peroxide treatments to enhance their adsorption capabilities, while copper nanoparticles are incorporated into the membrane to bolster its antimicrobial properties. Through comprehensive characterization techniques, including Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), dynamic light scattering (DLS), and scanning electron microscopy (SEM), we confirm the structural and chemical properties of the composite membranes. Batch adsorption studies reveal the superior performance of the composite membrane compared with individual components. Specifically, at lower methylene blue concentrations (∼20 ppm), the composite membrane demonstrates a remarkable percent removal value of about 97%, while at higher concentrations (∼100 ppm), the percent removal remains substantial at 85%. Additionally, desorption studies elucidate the retention capacity of the adsorbed dye, indicating the feasibility of the composite membrane for practical applications in wastewater treatment. These findings underscore the potential of nanocomposite-fiber membranes as sustainable and cost-effective solutions for mitigating water pollution. By harnessing advancements in nanotechnology and materials science, the presented innovative composite membranes could offer promising avenues for addressing water pollution challenges and promoting environmental sustainability.