This study is part of an effort to valorize the Algerian Mediterranean flora, focusing more specifically on the plant species Rosmarinus officinalis L. The main objective was to analyze the chemical composition of its essential oils as well as to evaluate their toxicity and biological properties, notably their antimicrobial and antioxidant activities. The rosemary essential oil was extracted from the leaves and flowers of the plant by hydrodistillation using a Clevenger apparatus, with a yield of approximately 0, 62%. The physical indices of this essential oil closely align with AFNOR standards, showing an acid index of 2.24 and an ester index of 325,10. Chemical analysis performed by gas chromatography (GC) revealed the presence of 15 different compounds, representing about 92, 56% of the total identified components. The antibacterial activity was assessed using the agar diffusion method, testing several bacterial strains. The most significant effect was observed against Staphylococcus, with an inhibition diameter of 21 mm, thus demonstrating a positive impact of this essential oil on the tested microorganisms.Furthermore, the antioxidant capacity was measured using a free radical scavenging test with DPPH (2,2-diphenyl-1-picrylhydrazyl). The results showed a moderate antioxidant potential, with an activity level of 64% for plants cultivated in the Mostaganem region. In summary, this essential oil of Rosmarinus officinalis L. exhibits interesting biological activities, making it a promising candidate for therapeutic applications in traditional medicine, aromatherapy, as well as in cosmetic and culinary fields. Indeed, it is rich in multiple health and wellness benefits.