Ocimum sanctum Linn., commonly known as Holy Basil or Tulsi, is one of the most venerated plants in Indian traditional medicine and has been extensively utilized in Ayurveda, Siddha, and Unani systems. A member of the Lamiaceae family, O. sanctum is known for its remarkable pharmacological properties, including antioxidant, anti- inflammatory, antimicrobial, and anticancer effects. The plant contains a rich profile of bioactive constituents such as eugenol, rosmarinic acid, apigenin, ursolic acid, carvacrol, and various flavonoids and phenolic acids, many of which have demonstrated potent cytotoxic activity against a range of cancer cell lines. The current review aims to comprehensively explore the phytochemical composition and anticancer potential of Ocimum sanctum, with a particular focus on phenolic compounds and their analysis through modern techniques like High-Performance Liquid Chromatography (HPLC). In vitro and in vivo studies have provided compelling evidence supporting the role of O. sanctum in cancer prevention and therapy, though clinical validation remains sparse. The review advocates for future research emphasizing standardization, bioavailability, mechanistic studies, and clinical trials to fully unlock the therapeutic potential of this sacred plant.