The present study was to investigate the essential oil composition and the antioxidant evaluation of P. inuloides growing the Algerian Sahara. The chemical composition was determined using GC–MS method, and antioxidant properties were estimated by DPPH and β-carotene assays. The major components were δ-cadinene (24.0%), α-epi-cadinol (15.0%), α-cadinol (12.7%), α-muurolene (7.8%) and γ-cadinene (6.6%). The highest antioxidant activity by DPPH and β-carotene assays were reported for the ethyl acetate extract (IC50 = 14.4 µg/mL and 85.2%) which was also the most concentrated in total phenol and flavonoid contents (316.5 µgGAE/mg and 396.8 µgEQ/mg, respectively). The essential oil showed also a high antioxidant potential by β-carotene assays (85.3%). Furthermore, the present work represents the first report on the essential oil constituents of an Algerian P. inuloides.