Lepidium sativum seeds (LSS) from four regions of Morocco have been analyzed for their total chemical composition and antioxidant activities. In the seeds of this plant, the moisture content and yield were, respectively, 9.24–9.88% and 19.13–19.94% of dry weight. Chemical analysis of the seeds revealed amounts of fatty acids, sterols, and tocopherols. The most important fatty acids are linolenic acid (33%) and oleic acid (23%). The main sterol is β-sitosterol (50%); the vegetable oil of Lepidium sativum revealed an amount of tocopherol (∼1500–1900 mg/kg) with dominance of γ-tocopherol. The Folin–Ciocalteu trial evaluated the total phenolic compound, DPPH radical scavenging, ABTS, and chelated iron ions. FRAP measured antioxidant potency. Results indicated that methanol extract from Lepidium sativum was a more potent reducing agent and radical scavenger than ethanol extract. Changes in the total phenolic content and antioxidant capacity of Lepidium sativum in four different regions grown under normal conditions were evaluated. The antioxidant activity of different extracts was found to correlate significantly with their total phenolic content. These results suggest that Lepidium sativum seeds could be used in food supplement preparations or as a food additive, for caloric gain or for protecting against oxidation in nutrient products.