HMAS Adelaide left Brisbane on Friday and will take five days to reach Tonga.
It has been loaded with humanitarian and disaster relief supplies, along with critical equipment to help with recovery efforts, including three Chinook helicopters.
The HMAS Adelaide will serve as a base for relief work in Tonga in the wake of the underwater volcanic eruption and following tsunami.
Meanwhile New Zealand will provide an extra $2 million in humanitarian aid for Tonga, on top of the $1 million already provided by the nation.
The country's foreign minister Nanaia Mahuta said the additional funds would be used for critical supplies such as drinking water, food and engineering equipment to clear debris.
Three New Zealand navy ships are heading to Tonga with supplies.
Delivery will be contactless, in order to comply with Tonga's COVID-19 protocols.
Of the $2 million being sent over, $1.5 million of that will go towards deploying more relief supplies, while the remaining $500,00 will part of a disaster response partnership.
Foreign Minister Marise Payne said she spoke to her Tongan counterpart and indicated further financial aid would be on its way.
Australia had initially offered $1 million in aid in the wake of the tsunami, but Senator Payne said that was likely to increase.
"There was $1 million for emergency supplies in the immediate aftermath, and there are further commitments to be made," she told ABC Radio.
"It's very difficult to estimate (the future cost) before those assessments are made by engineers and by the Tongan government itself in terms of what is needed."
Senator Payne said Australia would be standing with Tonga and providing as much support as needed.
Defence Minister Peter Dutton said Australia would be sending more planes to help with recovery efforts.
"We are working closely with the Tongan government to understand their needs," he told the Seven Network.
"They need support on the ground to help them rebuild as quickly as possible, in particular their communication system which has been done. That is a real problem."
An Australian C-17 plane landed in Tonga on Thursday afternoon with shelters, hygiene kits, along with water containers.
Air supplies had been delayed in getting into the country due to large amounts of volcanic ash being on the runway.
The offshore patrol vessel HMNZS Wellington - carrying hydrographic, dive personnel and a Seasprite helicopter - is checking shipping channels and wharf approaches to Tonga's port to ensure vessels can go alongside, and assessing the structural integrity of the wharf.
