A diverse array of functionally modified seaweed polysaccharide derivatives were prepared, which would be described in this account principally based on the reports published by us during the last decade. The modification reactions involved esterification, –C–N– bond formation and amidation reactions engaging the C-6 carbon of one of the repeating pyranose moieties of the polysaccharides of seaweed species growing in Indian waters, occasionally employing grafting and crosslinking reactions. The new functional properties that were imparted on the modified polysaccharides as a result, included fluorogenicity, thixotropicity, pH-responsiveness and gelling/swelling/metal ion absorbing properties. Of these, some properties were targeted, some were obtained fortuitously, and the latter included thixotropicity and photosensitizer activity. This article showcases various polysaccharide based new materials and the value added seaweed biomass, presenting potential opportunities in this area of research.