During 150 years, research at Station Biologique de Roscoff (SBR) has led to breakthroughs in the understanding of seaweed biology, ecology, systematics, biochemistry, genetics, and biotechnology. The possibility in staying in Roscoff to identify seaweed and their biology contributed at the turn of the XIXth century, to the first local flora encompassing more than 500 species. Renowned SBR's visitors pioneered the use of culture techniques to unravel life histories of not only brown algae but red and green seaweed. Others contributed to establish strong knowledge about kelp physiology or calcareous red algae. Since the turn of the XXth century, the increasing number of SBR permanent researchers contributed largely to a transformative period in studies of the evolution and functioning of seaweed groups, associated microbiota and their potential for novel applications, brought by high-throughput 'omic', genetic methods and system biology. The research at SBR has provided major contributions covering the ecosystemic importance of seaweed communities, the origin of algal groups, the holobiont concept and the link between phenotype and genotype, deciphered algal sex determination and explored the roots of algal multicellularity. The use of seaweed for food, feed, nutraceuticals, agro-solutions, green chemicals, or therapeutics was also promoted thanks to the development of glycobiology, 'omics' and microbial tools.