NSW will triple the size of its feral-free sanctuaries as it steps up efforts to bring back marsupials previously wiped out by threats such as cats and preserve other endangered creatures.
The Berejiklian government will spend $20.3 million to bring added protection to about 45,000 hectares of land already within national parks.
More than 50 threatened species are expected to benefit from the special zones.
Sarah Legge, an ecologist at the Australian National University, said Australia has already lost 34 mammals since Europeans arrived and there are at least eight more at risk from feral predators without the protection of fenced-off areas or island refuges.
Australians have been among the pioneers of so-called rewilding conservation efforts since the 1990s, Professor Legge said. All up, there are almost 65,000 hectares on feral-free zones on the mainland to date - of which just over 20,000 are in NSW.
That figure will jump by 45,000 hectares with the four new NSW sites, making it a "substantial increase", and the largest commitment of any state, territory or federal government, she said.