The US has legalised the transfer of nuclear-powered submarines to Australia, after lawmakers passed a defence policy bill.
Prime Minister Anthony Albanese heralded the milestone as "an extraordinary achievement".
The prime minister spoke to more than 100 members of the US Congress in the lead up to the vote.
"I pay tribute to all those who have worked hard to lobby members of Congress and Senate to achieve this," he told Sydney radio station 2GB on Friday.
"To get this legislation passed means that Australia will have access to those Virginia class submarines, which are nuclear-propelled and that will be so important for Australia's national security."
Washington is poised to sell Canberra at least three Virginia submarines, including two used vessels and one fresh off the production line.
The first is slated for the early 2030s.
Critical legislation enabling the sale, and for Australia to transfer almost $4.6 billion to prop up the American industrial base so submarines can continue rolling off the production line, passed the US House of Representatives early on Friday morning (AEDT).
The timing of the payment is being discussed between the two governments.
The National Defence Authorisation Act, which includes other measures such as a pay raise for US troops, will now go to President Joe Biden to be signed into law.
Defence Minister Richard Marles is confident future administrations will remain committed to the deal, with the president of the day able to halt the sale if it is against America's interest.
The bill had also been held up with some Congress members pushing for a stronger commitment from the Biden administration for the domestic manufacturing industry, to ensure the deal didn't adversely impact US submarine production.
"I am confident and the reason I am confident is because I think the critical thing that was demonstrated in the passage of this legislation is the bipartisan nature of this arrangement," Mr Marles told ABC TV.
The passing of the legislation was also welcomed by opposition defence spokesman Andrew Hastie.
"AUKUS is fundamentally a political project, uniting Australia with our friends, the US and the UK, in a shared ambition for a more peaceful, stable and secure world," he said.
Australia now needed to pull its weight and ensure it held up its industrial and economic commitment to the alliance, he added.
"Anything less will put the enterprise at risk," he said.
"We cannot have any weak links in this chain of stewardship."
The sale forms the keystone of the AUKUS pact between Australia, the UK and US.
The government has worked to tighten export control laws and to streamline technology sharing between the three nations to allow for smoother military collaboration.