Deverra tortuosa (Desf.) DC. is a notable xerophytic medicinal plant belonging to the Apiaceae family. Despite its recognized pharmacological value, phytochemical and antioxidant characterization of populations native to eastern Libya remains limited. This study evaluated the qualitative and quantitative phytochemical profiles and in vitro antioxidant capacity of Deverra tortuosa aerial parts collected in Benghazi, eastern Libya. Powdered plant material was extracted with 96.0% methanol and sequentially fractionated using n-hexane, ethyl acetate, and methanol. Qualitative screening detected phenols, tannins, flavonoids, coumarins, terpenoids, steroids, saponins, carbohydrates, proteins, amino acids, and cardiac glycosides, whereas alkaloids and free anthraquinones were absent. Spectrophotometric quantification demonstrated substantial reserves of specialized secondary metabolites, dominated by total coumarins (39.57±0.97), followed by terpenoids (29.31±0.96), flavonoids (27.82±0.93), and phenolics (8.58±0.14 mg GAE/g extract). The crude methanolic extract exhibited potent, concentration-dependent DPPH radical-scavenging activity, with percentage inhibition increasing from 57.30±0.56% at 250 µg/mL to 74.30±0.70% at 500 µg/mL, yielding a linear regression-derived IC₅₀ of 129.90 µg/mL. Qualitative TLC-DPPH testing corroborated strong free-radical scavenging capacity. These findings establish Deverra tortuosa from eastern Libya as a rich natural source of bioactive coumarins and natural antioxidants.