<p>Polysaccharide sulfotransferases (PSTs) catalyze the sulfation of polysaccharides, resulting in sulfated polysaccharides (SPs), which are abundant in marine macroalgae. Despite their importance, PSTs in macroalgae remain poorly characterized compared with sulfotransferases (STs) from plants, fungi, bacteria, and humans, necessitating the need for systematic genomic and biochemical analysis. This review discusses the various domains and families of sulfotransferases in brown, red and green macroalgae. It systematically evaluates the family of STs (sulfotransferase: 1, 2, 3, 15 and galactose-3-sulfotransferase 1) along with their respective genes, proteins, and amino acid lengths, and their functions across different species of brown and red macroalgae. Though studies on protein domains of sulfotransferases are available in green microalgae, they are perhaps under-reported in green macroalgae. The structures, domains, and functional conservation of carbohydrate sulfotransferases (CHSTs) share evolutionary relationships with those found in other taxa, including bacteria, plants, and humans. However, the CHST domains of red and brown macroalgae are more closely related than green algae. The role of sulfotransferases in the sulfation of the macroalgae is discussed along with the biological activities of SPs. Further sulfotransferase-mediated biosynthesis of SPs towards its own metabolism with respect to the extracellular matrix (ECM), detoxification, and environmental stress adaptation of marine macroalgae is also discussed. The recent advances in genomic and enzymatic studies of STs highlight possible avenues to develop rapid analysis of the enzymatic activity. This review provides a framework for elucidating the roles of marine macroalgal sulfotransferases in algal sulfation metabolism and SPs synthesis.</p>