Many alien species have been introduced around the world as part of the pet trade, and some have escaped captivity and become invasive. In South Africa, many species of tarantula (Theraphosidae) are kept as pets. It is not known which species are traded, which are most popular, and whether their names are correctly applied. Online traders and physical pet stores were investigated between 2015 and 2016 to determine the extent or size of trade, species composition, most popular species, and their invasion history elsewhere. In total, 36 specimens, three individuals from 12 putative species, were also purchased for DNA barcoding targeting the COI gene region to quantify the accuracy of tarantula identification by traders. In total, 195 tarantula species were advertised for sale, and the most popular species were Brachypelma albopilosum Valerio, 1980 (n = 199), B. vagans Ausserer, 1875 (n = 132), and Grammostola rosea Walckenaer, 1837 (n = 120). The composition of shared species differed between the sources and most of the species were advertised online. Only one of the popular species, B. vagans, has been recorded as being invasive elsewhere. Only 36% of the barcoded specimens matched existing barcodes in online repositories that had the same species name. The three individuals from 12 putative species were not in the same terminal clade as those of conspecifics in the Barcode of Life Data System (BOLD) and the NCBI GenBank reference sequences. A large proportion of the known tarantula species are traded in South Africa and must be included in management and risk assessments to avoid potential invasions.