Continental mountain areas cover less than 15% of global land surface, yet, these regions concentrate over 80% of global terrestrial diversity. One prominent hypothesis to explain this pattern proposes that high mountain diversities could be explained by higher diversification rates in regions of high topographic complexity. While high speciation in mountains has been detected for particular clades and regions, the global extent to which lineages experience faster speciation in mountains remains unknown. Here we address this issue using amphibians as model system (>7,000 species) and found that families showing high diversification rates contain a high proportion of species distributed in mountains. Moreover, we found that lineages inhabiting areas of high topographic complexity speciate faster than lineages occupying areas topographically less complex. When comparing across regions, we identified the same pattern in five biogeographical realms where higher speciation rates are associated with higher levels of complex topography. Low magnitude differences in speciation rates between some low and high complex topographies suggest that high mountain diversity is also affected by low extinction and/or high colonization rates. Nevertheless, our results bolster the importance of mountains as engines of speciation at different geographical scales and highlight their importance for the conservation of global biodiversity.