Sweet basil (Ocimum basilicum L.) is commonly used as an attractive flavor in Vietnamese cuisine and a valuable remedy in traditional medicine. The purpose of this study is to analyze the phytochemical profile, as well as to calculate the content of polyphenols and flavonoids and antioxidant activity of ethanolic and aqueous extracts from sweet basil leaves. The findings revealed that the leaves of sweet basil contained a wide range of pharmacologically active substances, such as alkaloids, coumarins, tannins, flavonoids, sugars, phenols, terpenoids and saponins. The total phenolic and flavonoid contents of ethanolic extract achieved 29.60 ± 1.64 mg GAE/g and 19.58 ± 0.93 mg QE/g, respectively. Furthermore, ethanolic extract displayed good antioxidant activities as shown in DPPH and ABTS radical scavenging methods, represented by IC50 of 91.31±4.28 µg/mL and 85.17 ±3.91µg/mL, respectively. These findings have shown that this plant is a potential source of natural antioxidants.