In recent years, companion animals have come to occupy an increasingly significant role in human life—not merely as pets, but as integral members of the family. As pet owners place growing emphasis on animal health and longevity, the demand for functional health ingredients has surged. Among these, fucoidan, a marine-derived polysaccharide extracted from brown seaweed, has emerged as a key player in the field of pet nutritional science. Recognized for its immunomodulatory, antioxidant, and cellular repair properties, fucoidan is redefining the standards for preventive care and holistic wellness in companion animals.