The Australian Defence Force will send Black Hawk and Chinook helicopters, fixed-wing aircraft and navy vessels to Victoria and NSW, the two worst-affected regions.
The military is expected to provide humanitarian assistance and carry out evacuations if needed in the coming days.
The US and Canada have also been asked to provide “specialist aviation resources” to help the emergency effort.
In his New Year message, Mr Morrison hailed the “amazing spirit of Australians” but warned that the weeks and months ahead would “continue to be difficult”.
The bodies of the latest victims – a 63-year-old man and his 29-year-old son – were found near the town of Corbargo in NSW.
Police said the men, named as Robert Salway and his son Patrick by Australian media, had stayed behind to protect their family home, where their bodies were found on Tuesday.
In Mallacoota, the local fire service said a change in wind direction had taken the worst of the fires away from the town.
“I understand there was a public cheer down at the jetty when that was announced,” said chief officer Steve Warrington.
About a dozen “emergency-level” blazes stretch across NSW and Victoria.
Several holiday spots along the coast have been cut off and the main road in the region – the Princes Highway – has been closed.
At midnight on Tuesday, Sydney’s A$6m (£3.1m; $4.2m) fireworks display, renowned worldwide, went ahead despite calls for it to be cancelled given the scale of the bushfire crisis.
Temperatures exceeded 40C (104F) in every state and territory at the start of the week, with strong winds and lightning strikes bolstering the flames.
Meteorologists say a climate system in the Indian Ocean, known as the dipole, is the main driver behind the extreme heat in Australia.