<p>This study aimed to valorize lignin, an abundant biomass waste product, by converting it into value-added antioxidants for lipid products. Lignin isolated from red oak via alkaline extraction underwent oxidative depolymerization using H₂O₂/CuSO₄ under reflux, followed by resin adsorption-desorption and further purified by ethyl acetate extraction to obtain phenolic enrich fraction (PEF). Characterization involved Fourier Transform Infrared Spectroscopy (FTIR) and Thin Layer Chromatography (TLC), while antioxidant properties were assessed using Total Polyphenol Content (TPC) and DPPH radical scavenging assays; efficacy as an oil antioxidant was tested using Ferric Thiocyanate and Anisidine Value methods under accelerated oxidation. The H₂O₂/CuSO₄ oxidation yielded approximately 60% lignin conversion, with FTIR confirming structural changes indicative of depolymerization. The PEF exhibited the highest TPC (26.57%GAE) and strongest DPPH scavenging activity (antioxidant activity index AAI = 1.84), significantly higher than raw lignin. In peanut oil, PEF demonstrated comparable initial peroxide inhibition (67% at 18&#xa0;h) to BHT, though BHT provided longer-term stability against secondary oxidation. In conclusion, oxidative depolymerization using H₂O₂/CuSO₄ effectively converts lignin into potent antioxidants, with the PEF fraction showing significant promise as a natural antioxidant for lipid-based products, thus offering a sustainable route for lignin valorization and contributing to waste management.</p> Graphical abstract <p></p>