Natural hair oils represent a cornerstone of cosmetic science, combining traditional ethnobotanical knowledge with modern formulation strategies. Defined as lipid-based extracts from plant seeds, fruits, or kernels, natural oils provide multifunctional benefits, including nourishment, scalp conditioning, and hair protection. Their significance lies not only in personal care and cultural heritage but also in their bioactive composition rich in triglycerides, fatty acids, and phytochemicals that deliver antioxidant, antimicrobial, and emollient properties. Commonly studied oils such as coconut, argan, olive, castor, almond, and neem have demonstrated efficacy in reducing protein loss, enhancing shine, improving scalp health, and addressing dandruff. Contemporary research extends its application into emulsion-based serums, sprays, and multifunctional blends. While consumer demand increasingly favours herbal, organic, and cold-pressed oils, safety considerations—such as dermatological sensitisation, oxidative stability, and regulatory compliance—remain central. Emerging innovations include nanoemulsions, microencapsulation, vitamin fortification, AI-driven personalisation, and sustainable sourcing. These trends reflect a shift toward evidence-based, eco-conscious, and consumer-tailored formulations. The cosmetic relevance of natural hair oils thus depends on balancing efficacy, safety, and sustainability, underscoring their continuing potential as a major research frontier in interdisciplinary cosmetic science.