This work aimed to extract hemp seed oil using modified supercritical CO₂ with ethanol, while optimizing the overall process through response surface methodology. The effects of extraction temperature (30-60 °C), pressure (10-20 MPa), and time (120-300 min) on oil yield, total phenols (TPC), total tocopherols, oxidative stability index (OSI), total chlorophylls, total carotenoids, quality indices, and color were assessed. For a maximum yield of 28.83 g/100 g of fresh seeds, the oil was extracted at 50 °C and 20 MPa for 244 min. In addition, CO₂ modified with different proportions of ethanol (2.5-20%) under the optimized SFE conditions was also tested for enhancing phenolic compound extractability in hemp seed oil. The best proportion was 10% ethanol, which significantly increased the oil yield to 30.13%, TPC to 294.15 GAE mg/kg, total tocopherols to 484.38 mg/kg, and OSI to 28.01 h, without affecting the quality parameters and the fatty acid profile. Furthermore, the phenolic compounds in the extracted oils were analyzed via HPLC-DAD/ESI-MS². These findings indicated that CO₂ modified with ethanol enhanced the extraction of phenolic compounds, 26 of which were identified. Among these, the most abundant compounds were N-trans-caffeoyltyramine, and cannabisins A and B, with concentrations of 50.32, 13.72, and 16.11 mg/kg oil, respectively. The oil obtained by SFE with SC-CO₂ + ethanol could be valorized by evaluating its biological activities and its anti-aging, dermato-protective and antimicrobial properties for use in the cosmetics, pharmaceutical and food applications.