PCR ribotype (RT) 017 ranks among the most successful strains of in the world. In the past three decades, it has caused outbreaks on four continents, more than other ‘epidemic’ strains, but our understanding of the genomic epidemiology underpinning the spread of RT 017 is limited. Here, we performed high-resolution phylogenomic and Bayesian evolutionary analyses on an updated and more representative dataset of 282 non-clonal RT 017 isolates collected worldwide between 1981 and 2019. These analyses place an estimated time of global dissemination between 1953 and 1983 and identified the acquisition of the -positive transposon Tn as a key factor behind global emergence. This coincided with the introduction of clindamycin, a key inciter of infection, into clinical practice in the 1960s. Based on the genomic data alone, the origin of RT 017 could not be determined; however, geographical data and records of population movement suggest that RT 017 had been moving between Asia and Europe since the Middle Ages and was later transported to North America around 1860 (95 % confidence interval: 1622–1954). A focused epidemiological study of 45 clinical RT 017 genomes from a cluster in a tertiary hospital in Thailand revealed that the population consisted of two groups of multidrug-resistant (MDR) RT 017 and a group of early, non-MDR RT 017. The significant genomic diversity within each MDR group suggests that although they were all isolated from hospitalized patients, there was probably a reservoir of RT 017 in the community that contributed to the spread of this pathogen.