Defence Minister Richard Marles announced the deal alongside his UK counterpart Grant Shapps as the pair convened for the annual AUKMIN meeting in Adelaide on Friday.
As part of the submarine construction process, Australia will hand $4.6 billion to the British shipbuilding industry to boost capacity at the Rolls-Royce factory in Derby and bankroll the design costs of the boats that Australia will build.
While defence firm BAE Systems will construct the submarines at the Osborne shipyards in Adelaide, the nuclear reactors used to propel the vessels will be made by Rolls-Royce in the UK.
Government-owner shipbuilder ASC was awarded the contract to sustain the AUKUS fleet. The company currently maintains the navy's fleet of conventional Collins class submarines.
Speaking after the ministerial get-together, Mr Shapps and Mr Marles made clear the investment was partially intended to combat the threat of Chinese militarism.
"AUKUS is of course, fundamentally about freedom of navigation," Mr Shapps told reporters.
"It's about ensuring that the world's oceans are capable of being sailed freely, as they should be, including here in the Indo-Pacific, including in the South China Sea."
Australian Foreign Affairs Minister Penny Wong and her UK counterpart David Cameron also took part in the AUKMIN meeting.
The two parties resolved to continue to support Ukraine's military, fight against the roll-back of human rights across the world and deepen ties with countries in the South Pacific.
In a joint statement, the ministers expressed their "deep concern at the catastrophic humanitarian crisis in Gaza" and reaffirmed their support for a two-state solution.
"Ministers called on Israel to allow immediate, safe, unimpeded and increased humanitarian relief to reach Palestinians in Gaza," the statement read.
"Given the large number of displaced persons taking refuge in the area and lack of safe spaces in Gaza, ministers shared deep concern at the potentially devastating consequences for the civilian population of an expanded Israeli military operation in Rafah."
Mr Shapps and Mr Cameron capped their diplomatic mission with some cultural enrichment - watching the Crows take on Geelong at Adelaide Oval in the AFL.
"What we are about is maintaining a global, world based order. It's something we hold particularly dear," Mr Shapps said.
"Which is why I'm slightly surprised to be going to an Australian footy match later, where the world order of rules is something of a mystery to me."
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