Tulsi is a Sanskrit word that means “matchless one”. Ocimum sanctum is a plant of family Lamiaceae, is commonly known as Holy Basil. Characteristically, the plant imparts a pungent, bitter, hot, light and dry effect. Holy Basil is extensively famous and has been used since centuries in Ayurvedic and Greek medicines owing to its beneficially diverse properties. O. sanctum (Tulsi in Hindi) has a significant place in Hindu culture, being used in an array of traditional medicaments and as a condiment. Online published articles, journals, internet sites, Pubmed, Scopus and Google Scholar were explored for data collection. Since Ayurveda times, various parts such as leaves, roots, seeds and whole plant has been recommended for treatment of a spectrum of diseases including bronchitis, dysentery, malaria, diarrhea, eye ailments, dermatological issues, rheumatoid arthritis, etc. Scientifically, it has been proven that O. sanctum possesses anticancer, anti-diabetic, anti-fertility, antifungal, antimicrobial, cardio protective, analgesic, antispasmodic and adaptogenic, immunomodulatory, antioxidant, hepatoprotective, antiallergic, antipyretic, antiviral, antiulcer, anti-inflammatory, CNS depressant and anti-arthritis activities. Its biologically active constituent is known as Eugenol (1-hydroxy-2-methoxy-4-allylbenzene) which is responsible for the mediation of therapeutic characteristics. This review is an attempt to summarize the botanical, pharmacological, phytochemical, ethno medicinal, and toxicological information. This is an effort to help researchers and clinicians to be aware of the magical properties and the effectiveness of Tulsi.