Cannabis sativa L. is a multifunctional plant of growing global importance for industrial, nutritional, and medicinal uses. Despite numerous publications, existing reviews often treat its botanical, chemical, and therapeutic aspects separately. The present work aims to provide an integrative synthesis of the species botanical diversity, phytochemical composition, and therapeutic promise, while highlighting the current gaps and future research needs. Accordingly, This review compiles and critically analyzes over 200 recent peer-reviewed studies (2016–2025) covering the taxonomy, morphology, secondary metabolite biosynthesis, and pharmacological applications of C. sativa. Data were compared across different plant varieties, geographical origins, and extraction techniques to reveal patterns and inconsistencies in chemical composition and biological activity. The analysis revealed more than 550 identified compounds, including over 120 cannabinoids and 150 terpenoids. The relative abundance of major cannabinoids (Δ⁹-THC, CBD, CBG, CBC, CBN) depends strongly on genotype, climatic conditions, and processing methods. Phytochemicals from C. sativa exhibit potent antioxidant, anti-inflammatory, neuroprotective, and anticancer activities. However, the lack of standardized extraction, quantification, and clinical evaluation protocols limits reproducibility and pharmacological validation. Most available data derive from preclinical models or chemically undefined extracts, complicating translation to therapeutic use. Future work should integrate genomic, metabolomic, and clinical approaches to clarify structure-activity relationships and ensure product safety and efficacy. This synthesis provides a consolidated scientific framework useful for researchers, clinicians, and industry stakeholders seeking to optimize Cannabis sativa utilization for pharmaceutical, nutraceutical, and biotechnological development. Unlike previous reviews, this article offers a cross-disciplinary perspective linking the plant’s botanical morphology, chemical diversity, and therapeutic mechanisms. It identifies critical research gaps that must be addressed to transform C. sativa from a controversial crop into a standardized bioresource.