In this study, the various extracts of aerial parts of Helianthemum sessiliflorum Pers. were examined in vitro for possible source of antioxidants and for antibacterial activity. The antioxidant activity was performed by DPPH radical scavenging method which showed that ethyl acetate extract possessed the best antioxidant potential (IC50 = 32.75 ± 2.07 μg/mL). The significant linear correlation was realised between the values of the total phenolic/flavonoid content and antioxidant activity of plant extracts. The ethyl acetate and n-butanol extracts showed moderate antibacterial activity. In addition, the phytochemical study of n-butanol extract afforded nine known phenolic compounds (1-9). This is the first report of six of them (1, 3, 5-8) in Cistaceae family. The structural identification of the isolated compounds was achieved using several spectroscopic methods.