This investigation explored the chemical constituents and biological activities of the steam-distilled oil of L. usitatissimum (SDOLU), employing sophisticated techniques including LC-HRMS, GC-MS, and GC-FID. The analysis identified a diverse array of 17 phenolic compounds, with linoleoyl chloride (64.05%) and linoleic acid (10.39%) as the major fatty acid components. The SDOLU demonstrated remarkable antioxidant capacity, effectively neutralizing free radicals in both DPPH^• (IC₅₀: 19.80 μg/mL) and ABTS^•+ (IC₅₀: 57.75 μg/mL) scavenging assays, alongside robust electron-donating activity in reducing ability tests. Moreover, the SDOLU showed significant inhibition of key enzymes implicated in metabolic and neurodegenerative disorders, including α-amylase (IC₅₀: 531.44 μg/mL), acetylcholinesterase (IC₅₀: 13.23 μg/mL), and carbonic anhydrase II (IC₅₀: 281.02 μg/mL). Collectively, these results highlight the SDOLU as a valuable natural source of multifunctional bioactivities with potential applications in combating oxidative stress and enzyme-related global diseases. Further studies are warranted to validate its therapeutic efficacy and expand its industrial utilization.