Pomegranate (Punica granatum L.) is a nutritionally rich fruit widely recognized for its diverse therapeutic properties and extensive applications in food, pharmaceutical, and cosmetic industries. This review provides a comprehensive overview of the composition, bioactive constituents, and biological activities of different parts of the fruit, including arils, seeds, and peel. Pomegranate is abundant in polyphenols such as ellagitannins (punicalagin and punicalin), ellagic acid, flavonoids, and anthocyanins, which contribute significantly to its pharmacological effects. The arils are a rich source of sugars, vitamins, and antioxidants, exhibiting strong antioxidant, antimicrobial, and prebiotic activities. Seeds contain bioactive lipids, particularly punicic acid, associated with anti-inflammatory, cardioprotective, antidiabetic, and anticancer effects. The peel, often considered agro-industrial waste, is highly enriched with phenolic compounds and demonstrates potent antioxidant, antimicrobial, antiviral, and anti-inflammatory properties. Recent advances in extraction techniques and nanoformulation strategies have further enhanced the bioavailability and applicability of these bioactive compounds. Overall, pomegranate and its by-products represent valuable natural resources with significant potential for the development of functional foods, nutraceuticals, and therapeutic agents. Further research is required to optimize extraction methods, understand molecular mechanisms, and explore clinical applications.