Seaweed-derived polysaccharides including carrageenan, alginate, ulvan, and fucoidan have garnered increasing attention for their multifunctional bioactivities and biocompatibility, positioning them as promising agents in tissue engineering, regenerative medicine, and gastrointestinal therapy. These marine biopolymers exhibit broad spectrum of therapeutic properties such as antioxidant, anti-inflammatory, antimicrobial, and immunomodulatory effects. In wound repair and tissue regeneration, they support cell proliferation, enhance mechanical stability, and enable controlled delivery of bioactive compounds. In the context of inflammatory bowel disease (IBD), polysaccharides from green (Ulva), red (Porphyra, Gracilaria), and brown (Laminaria, Undaria) algae have demonstrated significant benefits in experimental models by modulating immune signaling pathways, restoring gut barrier integrity, and promoting beneficial microbiota and metabolite profiles. Advanced applications including fucoidan-based bioinks for 3D bioprinting and polysaccharide-derived nanocarriers further highlight their potential in drug delivery and therapeutic modulation. Overall, seaweed polysaccharides represent a promising class of natural biomaterials with wide-ranging biomedical applications, warranting continued research and clinical translation. © 2025 Elsevier B.V., All rights reserved.