The ADF will help respond to fires raging in Victoria's East Gippsland where four people are missing in blazes that have destroyed homes.
The state government has also announced a bushfire response taskforce it vows will avoid "red tape" in dealing with fallout from the blazes.
The developments come after lightning sparked more than a dozen new blazes in Victoria's alpine region on Tuesday.
Prime Minister Scott Morrison confirmed the military support on Tuesday afternoon.
"This afternoon I have spoken with Victorian Premier Daniel Andrews regarding the devastating fires in Victoria. Our Governments are working closely together, including our defence forces," Mr Morrison wrote on Twitter.
Defence Minister Linda Reynolds said aerial assets will be deployed. "Three helicopters & 1 aircraft will fly to East Sale," she said in a post on Twitter.
State cabinet's security and emergencies management committee met on Tuesday afternoon and established a bushfire response and recovery taskforce, to be led by Andrew Crisp.
'No red tape'
Victorian Emergency Services Minister Lisa Neville said the taskforce is aimed at ensuring "no barriers, no red tape, no bureaucracy" get in the way of meeting immediate needs and a broader response.
Victorian emergency commissioner Andrew Crisp told reporters "we expect those additional Australian Defence Force people to be on the ground tomorrow working with our Metropolitan Fire Brigade".
Mr Crisp said up to 40 military personnel will help assess the fire damage from Wednesday.
Authorities are also considering other ways the military could provide support, such as fixed-wing planes and helicopters.
Requests for 70 firefighters have also been made to Canada and the United States.
Four people missing, 43 buildings destroyed
Premier Daniel Andrews said there are four people unaccounted for and their whereabouts cannot be confirmed.
"We do have very real fears for their safety," said Mr Andrews, who added they are not firefighters.
The premier returned from leave with his family on the Mornington Peninsula to respond to the crisis.
"These are really significant events, people have lost their homes, we may well be talking about lives lost, so the best place for me is to be here, to be briefed, to be across these details," he said.
A total of 400,000 hectares of land has been burnt from fires in the state's east, Emergency Management Commissioner Andrew Crisp said.
A total of 400,000 hectares of land has been burnt from the bushfires in the state's east
He said at least 43 buildings were lost in East Gippsland and that number is likely to grow.
Victorian Education Minister James Merlino has confirmed Clifton Creek Primary School in East Gippsland has been destroyed by fire.
Conditions ease in Mallacoota
Thousands of people are seeking support at about a dozen relief centres in the state.
Milder weather is expected over the next 24 hours, giving firefighters some reprieve, but Mr Crisp said people in East Gippsland must remain vigilant.
"No one can afford to relax in that part of the state," he said.
The coastal town of Mallacoota was hit by fire on Tuesday morning, sending at least 4,000 people to the beach for shelter.
But CFA chief officer Steve Warrington said there was some good news from the area.
"The wind change has gone through and the major fire front has now bypassed that town," he said.
"But having said that, there are still active fires in that area and they're still actively extinguishing houses that have burnt down on the outskirts of Mallacoota."
The Bureau of Meteorology says the temperature spiked at 49C at Mallacoota around 8am.
The bureau believes that fire-affected air, or fire itself, moved past the weather station at the time, with the mercury dropping to 24C just 10 minutes later.
The blazes have cut power to homes, with AusNet Services reporting 5700 properties without electricity in East Gippsland, with another 1800 in northeast Victoria.
The energy company expects it could take days to restore power.
