Rosemary has played an important role from past to present and has antimicrobial, antifungal and antioxidant properties. With these features, it is used in many sectors, especially food and pharmacy. Rosemary essential oils have a positive effect on biological activity. In addition, this oil prevents lipid oxidation on foods, providing a long and fresh shelf life. Due to the high antioxidant properties of rosemary, it eliminates the harmful effect of reactive oxygen species. Since the main components of rosemary such as 1,8-cineol, camphor, α-pinene, carnosic acid, and carnosol are being antimicrobial and antifungal, it is effective against many pathogens. With this review, it is aimed to provide comprehensive information on the biological activities of rosemary and its extracts to shed light on future research.