Eastern and southern Australia
A patchy range through eucalypt forest and woodland — and a few places they were introduced.
The Australian Museum describes a patchy distribution from northern Queensland to southern Victoria and south-eastern South Australia. Australian Museum: Koala The Queensland Government likewise places them across much of Queensland, New South Wales, Victoria and a small area of South Australia, in open forest and woodland where the right food trees grow. Queensland Government: Koala facts
The IUCN lists the koala as native and extant in New South Wales, Queensland, South Australia and Victoria. IUCN Red List: Koala (Phascolarctos cinereus) Habitat is defined by a select group of food trees; densities are higher on more fertile soils and along watercourses, and they can remain in partly cleared and urban areas. Queensland Government: Koala facts
The IUCN notes introductions to at least 12 islands, including Kangaroo Island in South Australia and French and Phillip Islands in Victoria, and a mainland introduction in the Adelaide region. IUCN Red List assessment PDF: Koala (Phascolarctos cinereus)
Fossil records show koalas once inhabited parts of Western Australia and the Northern Territory; there are no fossil records of them in Tasmania. Queensland Government: Koala facts