<p>This study presents the green synthesis and comprehensive characterization of xylan/cellulose (XC²L) nanocomposites crosslinked with catechol (derived from potato extract) and stabilized by lecithin (extracted from soybean). Fourier-transform infrared spectroscopy (FTIR) confirmed successful functionalization through characteristic phenolic (O–H, C = C, C–O) and phosphorous (P = O, P–O–C) stretching bands. X-ray diffraction (XRD) analysis indicated enhanced crystallinity in the cellulose-rich composite (XC²L-3), while zeta potential and dynamic light scattering (DLS) analyses revealed good electrostatic stability (− 19.47 mV for XC²L-1) and nanoscale particle sizes (124–13,815&#xa0;nm). Scanning electron microscopy (SEM) showed smoother surface morphologies upon lecithin incorporation. Functionally, XC²L-4 exhibited superior water absorption (1.80% at 22&#xa0;°C), strong antioxidant capacity (IC₅₀ = 17.57&#xa0;µg/mL), and remarkable antimicrobial activity against <i>Staphylococcus aureus</i>, <i>Escherichia coli</i>, and <i>Candida albicans</i>. These findings demonstrate that the synergistic action of catechol and lecithin enhances the structural, antioxidant, and antimicrobial performance of xylan/cellulose nanocomposites, offering a sustainable platform for biodegradable packaging and biomedical applications.</p> Graphical Abstract <p></p>