Abstract: As an important renewable marine bio-resource, the high-value utilization of seaweed has garnered significant attention in current research and industry. This paper reviews the main nutritional components（e.g., proteins, lipids, polysaccharides, minerals, vitamins）and bioactivities of seaweed, with a focus on processing technologies and their latest applications in diverse fields. In the food industry, seaweed is developed into various novel healthy foods, and its extracts can serve as natural additives. Its active ingredients show significant promise in the functional food and pharmaceutical sectors, holding importance for chronic disease prevention. In cosmetics, seaweed extracts are key natural skincare ingredients. Furthermore, seaweed-based biomaterials offer unique advantages for environmentally degradable materials and advanced biomedical applications. Despite its promising prospects, the high-value utilization of seaweed still faces multifaceted challenges, including resource scarcity, immature technology, and market competition. Therefore, future research should focus on key directions such as efficient resource utilization, advances in processing technology and intelligent upgrading, in-depth exploration of bioactive mechanisms, and industrial transformation, in order to systematically promote the high-value development and sustainable utilization of seaweed resources.