Sea buckthorn leaves are an abundant natural resource with considerable application potential. In recent years, significant progress has been made in the study of the bioactive components and physiological effects of sea buckthorn leaves. Sea buckthorn leaves are rich in flavonoids, polysaccharides, polyphenols, terpenoids, and other active components, exhibiting biological functions such as anti-inflammatory, antioxidant, blood glucose/lipid regulation, and hepatoprotective effects. This review comprehensively outlines the bioactive components of sea buckthorn leaves and their physiological functions, summarizes current applications and development status, and prospects future research directions. It provides a theoretical reference for the deep processing and efficient utilization of sea buckthorn leaf resources.