It is found in mid-eastern New South Wales and at least formerly Victoria, where it ranges from Carrai National Park south to East Gippsland.

[1] Long considered to comprise southern populations of the stuttering frog (M. balbus), it was not recognised as a new species until 2023, when a phylogenetic study found it to be deeply divergent from M. balbus and thus described it as a new species.

[2] The distributions of the northern and southern stuttering frogs are separated by the Macleay River.

[3] This species has disappeared from two-thirds of its distribution, and thus qualifies for Endangered on the IUCN Red List.

Unlike M. balbus, which is a high-altitude specialist, both upland and lowland populations of M. australis have been recorded.