<p>In this study, bio-based nanocomposites were synthesized by combining xylan and cellulose in a 70:30 weight ratio, utilizing glutaraldehyde (2% v/v) as a cross-linking agent and Tween 80 (1% v/v) as a surfactant. Characterization via Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), dynamic light scattering (DLS), and zeta potential analysis confirmed the successful cross-linking and nanoscale structure of the composites, with an average particle size of 212.6 ± 8.3&#xa0;nm and a zeta potential of − 32.0 ± 1.2 mV indicating good colloidal stability. Electrochemical studies in 3.5% NaCl solution revealed a corrosion inhibition efficiency of 82.4%, as determined by Tafel polarization, and a charge transfer resistance increase from 0.42 kΩ.cm² to 4.82kΩ.cm², as observed in electrochemical impedance spectroscopy (EIS), confirming enhanced anticorrosive behaviour. Additionally, UV-Vis spectroscopy demonstrated highly sensitive and selective metal-ion sensing capabilities, with detection limits of 158 µM for Fe³⁺ and 135 µM for Cu²⁺, accompanied by distinct colorimetric changes. These findings underscore the potential of cross-linked xylan/cellulose nanocomposites as sustainable materials for both corrosion protection and environmental monitoring applications.</p>