The Australian government will take three, potentially second-hand Virginia-class submarines early next decade, pending the approval of the US Congress.
The nuclear submarine programme will cost up to A$368 billion (NZ$394.5b) over the next three decades.
There will also be an option to purchase another two under the landmark AUKUS defence and security pact, announced in San Diego on Tuesday morning.
In the meantime, design and development work will continue on a brand new submarine, known as the SSN-AUKUS, "leveraging" work the British have already been doing to replace their Astute-class submarines.
That submarine - which will form the AUKUS class - would eventually be operated by both the UK and Australia, using American combat systems.
One submarine will be built every two years from the early 2040s through to the late 2050s, with five SSN-AUKUS boats delivered to the Royal Australian Navy by the middle of the 2050s.
Eventually, the fleet would include eight Australian submarines built in Adelaide into the 2060s, but the federal government is leaving open the option of taking some from British shipyards if strategic circumstances change.
Meanwhile, the federal government estimates the cost of the submarine programme will be between A$268b and A$368b over the next 30 years.
As part of that figure, A$8b will be spent on upgrading the naval base HMAS Stirling in Western Australia.
From as early as 2027, four US and one UK submarine will start rotating through Western Australia, to be known as the Submarine Rotational Forces West.
No decision has been made on a future east coast base for submarines, although Port Kembla has firmed as the most likely location.
Standing alongside Prime Minister Anthony Albanese and UK Prime Minister Rishi Sunak, US President Joe Biden spoke of the strength of the alliance already.
"Today, as we stand at the inflection point in history, where the hard work of announcing deterrence and enhancing stability is going to reflect peace and stability for decades to come, the United States can ask for no better partners in the Indo-Pacific where so much of our shared future will be written," Biden said.