The ocean is par excellence a fertile territory of biodiversity on our planet. Marine-derived polysaccharides have been applied as functional materials in biomedicine due to their attractive bioactive properties, safety, high availability and low-cost production. Laminarin (or laminaran), a low molecular weight β-glucan storage polysaccharide present in brown algae, can be (bio-) chemically modified to enhance its biological activity and employed in cancer therapies, drug/gene delivery, tissue engineering, antioxidant and anti-inflammatory functions. This review provides a brief overview on laminarin characteristics, modification strategies and highlights its pivotal biomedical applications.