Australian soldiers will depart Darwin to help train Ukrainian troops as Kyiv continues to repel Russia's invasion.
Up to 70 Australian personnel will join partner nations in Britain to help boost the infantry tactics and military skills of Ukrainians.
No Australian troops will enter Ukraine.
The United Kingdom-led program is aiming to train up to 20,000 Ukrainian soldiers this year.
Deputy Prime Minister and defence minister Richard Marles said Australia continues to stand with the embattled nation after Russia's "clear violation of the rules-based order".
"Operation KUDU builds on Australia's military support for Ukraine, with the previously gifted Australian-produced Bushmaster protected mobility vehicles proving their worth as highly valuable military vehicles," he said.
Defence Personnel Minister Matt Keogh said military personnel were "our greatest defence capability".
"That's why it's so important that our soldiers, alongside a number of partner nations, will provide essential skills to the armed forces of Ukraine, supporting Ukraine to end the conflict on its own terms."
The personnel will primarily be drawn from the army's first brigade and will be formally farewelled in Darwin on Wednesday.
Mr Marles will send a personal video message to the departing Australians.
Australia has provided about $655 million in support for Ukraine, including $475 million in military assistance.
It includes a total of 90 Bushmasters.