This study aims to explore the potential of Algerian milk thistle (Silybum marianum) seeds for food application. Solid–liquid extraction and Soxhlet extraction methods were employed to obtain both aqueous and fatty fractions using different solvents. Spectrophotometry was used to assess the content of bioactive compounds and pigments, while gas chromatography–mass spectrometry (GC-MS) analyzed the fatty acid composition. Additionally, the oxidative stability of the plant oil was evaluated using the Rancimat test. The results indicated a moisture content of 0.779% and a plant oil extraction yield of 0.278%. The polyphenol content in the oil was measured at 142.66 mg/100 g. The choice of solvent significantly impacted the content of bioactive compounds, with the highest values observed in the 80% methanol extract for total polyphenols, the aqueous extract for total flavonoids, and the ethanol extract for reducing power. Furthermore, the present study quantified pigments including chlorophyll, carotenoids, anthocyanins, and carotenoids. GC-MS analysis revealed a diverse range of fatty acids typical of edible oils, including essential fatty acids from the ω3, ω6, and ω9 series. The Rancimat test indicated an oxidation resistance of 14.65 h. Overall, the findings suggest that Silybum marianum holds promise as an edible oil source rich in antioxidants, micronutrients, and essential fatty acids.