Invasive species can have competitive advantages in non-native ranges through decreased pathogen pressure or through the spread of invasive pathogens that spillover to native species. The common myna (Acridotheres tristis), one of the world's most invasive species, carries a high prevalence of avian malaria (Plasmodium and Haemoproteus spp.) in its native range and is a fierce competitor in its introduced Australian range. We tested whether this competitive advantage stems from pathogen release by comparing malaria prevalence between introduced and native mynas and relating these to prevalence in native Australian birds. We also used a global database of malaria DNA sequences to identify potentially invasive malaria lineages carried by introduced mynas. Malaria prevalence did not differ between introduced and native mynas. However, compared to native birds, Plasmodium prevalence was significantly higher in introduced mynas while Haemoproteus prevalence was significantly lower. Nine Plasmodium lineages were shared between Australia and the myna's native range, and eight of these occurred in both introduced and native mynas. Importantly, four of these shared lineages were also found infecting Australian native birds despite strong phylogeographic evidence for their origination in the myna's native range. We propose that mynas experience a competitive advantage by avoiding Haemoproteus infections in Australia and by harbouring introduced Plasmodium lineages that occasionally spillover to native birds.