Streptococcus pyogenes (Group A streptococcus; GAS) is responsible for over 500,000 deaths worldwide each year. The highly virulent M1T1 GAS clone is one of the most frequently isolated serotypes from streptococcal pharyngitis and invasive disease. The oral epithelial tract is a niche highly abundant in glycosylated structures, particularly those of the ABO(H) blood group antigen family. Using a high throughput approach, we determined that a strain representative of the globally disseminated M1T1 GAS clone, 5448, interacts with numerous, structurally diverse glycans. The highly abundant, surface exposed M1 protein showed high affinity for several terminal galactose blood group antigen structures. Deletion mutagenesis showed that M1 protein mediates glycan binding via its B-repeat domains. Association of M1T1 GAS with oral epithelial cells varied significantly as a result of phenotypic differences in blood group antigen expression, with significantly higher adherence to those cells expressing H-antigen structures compared to cells expressing A, B or A and B-antigen structures. These data suggest a novel mechanism for GAS attachment to host cells, and proposes a link between host blood group antigen expression and M1T1 GAS colonization.