Consumers are increasingly seeking natural alternatives to synthetic preservatives in meat products. This study evaluated the effects of willow E. angustifolium extract on beef burgers' physicochemical properties, color stability, and lipid oxidation during refrigerated storage. The extract demonstrated significant antioxidant activity, with a total phenolic content of 1263.48 mg GAE/L and a total flavonoid content of 278.43 mg CE/L. The pH values of the beef burgers decreased over time, with significant effects on Days 4 and 8 in the treated groups, except T1. The color properties, including lightness (L*), redness (a*), and yellowness (b*), were affected by the plant extract, with 1 g and 3 g concentrations leading to darker and redder hues. Moreover, adding 9 g extract led to discoloration due to increased b* values. Thiobarbituric acid-reactive substances analysis showed increased lipid oxidation, with the T3 group (9 g extract) exhibiting higher values, suggesting a prooxidant effect at higher concentrations. Gas chromatography–mass spectrometry analysis identified a range of phytochemicals, including α-pinene and β-thujone, which contributed to the complex, volatile profile of the extract. High-performance liquid chromatography analysis revealed the presence of significant phenolic compounds, such as ascorbic acid and gallic acid, with high antioxidant potential. Molecular docking studies indicated that gallic acid exhibited a moderate binding affinity with the target protein 9R-lipoxygenase (5EK8), followed by β-thujone and α-pinene, suggesting their potential as bioactive compounds in food preservation. The results provide insights into the functional potential of E. angustifolium extract as a natural antioxidant and preservative in meat products.