This study aims to assess the phytochemical composition and evaluate the antioxidant and antibacterial activities of the methanolic extract from the aerial parts of Artemisia campestris, which grows in Southeast Algeria. The results indicate that the plant is rich in proteins and lipids while exhibiting low carbohydrate content. Additionally, there were notable variations in the levels of polyphenols and flavonoids. The crude extracts were high in polyphenols content in the ethanol extract 446.7±5.11 mg EAG/g Extract, and the best value of flavonoids in methanol extract 66.8±0.93 mg QE/g Extract and 5.19±2.60 mg CT/g Extract. The HPLC analysis revealed that Rutin (16042.036 µg/g) and Chlorogenic acid (14224.476 µg/g) were the most abundant element with a high amount of Quercetin and Naringin (5884.808 µg /g, 2109.307 µg/g respectively), a moderate quantity of Vanilin, Gallic acid, Vanilic acid and Caffiec acid (864.363 µg/g, 740.516 µg/g, 733.753 µg/g and 669.865 µg/g), a little amount of p- Coumaric acid (216.626 µg/g). To evaluate the antioxidant activity, the results of the DPPH• test showed that methanol extract had a scavenging effect (IC50: 552± 0.7 μg/ml), 50% of erythrocytes could be protected at a concentration of 245.17± 5.8 μg/mg; this value was comparable to ascorbic acid's activity (IC50=85.29± 2.3 μg/mL). The high concentration of extract (25 mg/ml) had the best antibacterial activity using the disc diffusion method on two bacterial strains: Escherichia coli (13.66± 1.3 mm) and Enterococcus faecalis (18.33± 2.1 mm). The findings underscore the potential applications of Artemisia campestris in the agro- food and pharmaceutical industries.