This study introduces a novel approach by utilizing Aspergillus niger for the isolation of nanocellulose from date palm sheath fibers (DPSF), achieving significant nano-scale reduction and high yield efficiency. The enzymatic breakdown by Aspergillus niger efficiently reduced the fibers' size, achieving an 81.3 % transition to nano-scale (<100 nm) after 96 hours, with an impressive 84 % yield using 72 hours of fungal treatment. The isolated nanocellulose demonstrated superior thermal stability and zeta potential value of −32.5 mV indicates a stable colloidal suspension due to the electrostatic repulsion between nanocellulose particles. Triethoxymethylsilane (TEMS) modification of nanocellulose aerogel significantly improved mechanical strength from 0.0194 to 0.03614 N/mm². Treatment with 5 % TEMS reduced water absorption from 41.7 g/g to 11.3 g/g, enhancing hydrophobicity (water contact angle 136.21°) and shifting material preference away from water. TEMS-treated samples showed increased absorption capacities of up to 44.3 g/g for cooking oil and 57.6 g/g for motor oil, highlighting improved compatibility with non-polar substances. These advancements underscore a sustainable solution for oil spill remediation, offering significant potential in environmental conservation and recovery efforts.