The state's Labor opposition, which had previously voiced opposition to the 23,000-seat roofed stadium at Macquarie Point, on Monday announced it would back the project.
The stadium, slated to cost $715 million, is part of the island state's deal for entry into the AFL in 2028.
The project will be assessed by an independent planning commission and must be voted through both houses of parliament.
The governing Liberals, who signed the deal, command just 14 of 35 lower-house seats in minority and faced a tough ask to get the required numbers.
The stadium now has the backing of 10 lower-house Labor MPs.
Labor leader Dean Winter, who took over the role from anti-stadium Rebecca White after the election, said the change in position was about jobs.
"A stadium will mean thousands of jobs in construction, including hundreds of apprenticeships," he said.
"That's why Labor will be backing a new stadium.
"While we will not be standing in the way of the current Macquarie Point stadium proposal, we still hold concerns around the deliverability of the project."
Liberal Premier Jeremy Rockliff has promised to cap the state's spend on the project at $375 million.
Ms White had pledged to try to renegotiate the stadium deal if elected at the March 23 poll, saying it was not the right priority.
The two major parties could hold a majority in the upper house depending on the outcome of elections in three divisions held at the weekend.
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