This review briefly characterizes the major Australian seaweed groups that elaborate gelling non-fibrillar wall components; it surveys the research, mostly conducted in the past decade, into the structure and potential applications of their polysaccharides. Recent emphasis has been placed on the chemistry of red-algal galactans, which has provided a chemotaxonomic data set against which hypotheses of algal taxonomy and phylogeny derived from classical morphology can be tested. Although there are ongoing environmental and economic impediments to the establishment of seaweed-based industries in Australia, the phycocolloids from Australian-endemic algae show a chemical diversity and potentially exploitable properties unmatched by species from other world regions. Novel gelling polysaccharides are leading to the exploration of structure–property relationships that will in time promote the development of whole new classes of commercial applications. Future advances in the technologies of commercial processing are likely to result from a deeper understanding of the phycocolloid biosynthesis pathways displayed by Australia’s rich genetic store of native seaweeds.