Abstract: Fucoidan (Fuc) is a sulfate-rich, water-soluble heteropolysaccharide derived from marine brown algae. Recognized for its exceptional biocompatibility, biodegradability, and low toxicity, Fuc is a valuable component in the development of nanoparticle delivery systems. Nanoparticles present a promising delivery system by protecting sensitive substances from environmental factors while enabling controlled release. Despite numerous studies on fucoidan-based nanoparticles conducted both in China and internationally, a comprehensive review is still lacking. This paper begins by exploring the source, composition, and structure of Fuc. It then summarizes the primary methods for preparing Fuc based nanoparticles, including polyelectrolyte self-assembly, anti-solvent precipitation, and green synthesis. Additionally, the paper highlights their applications across food science, biomedicine, and antimicrobial materials. Finally, a bibliometric analysis is conducted to forecast future research directions for Fuc-based nanoparticles, providing valuable insights for their applications.