This study investigates the enhanced biosorption of Uranium (VI) from aqueous solutions using sodium hydroxide-pretreated Aspergillus niger biomass. Uranium contamination in aquatic environments poses significant environmental and health risks, and cost-effective removal methods are crucial. The pretreatment of Aspergillus niger biomass with sodium hydroxide aims to enhance its biosorption capacity for uranium. Batch biosorption experiments were conducted, assessing the influence of contact time, initial uranium concentration, pH, and biosorbent dosage on the biosorption process. The results demonstrate that sodium hydroxide pretreatment substantially increases the biosorption efficiency of Aspergillus niger for Uranium (VI), providing a promising and eco-friendly approach for uranium removal from aqueous solutions.