The Greens have voted to accept a deal with the Labour Party which will see the party's two highest-ranking MPs become Ministers outside of Cabinet.
After close to four hours of negotiations between key Green Party delegates, 84 per cent of voters backed the deal offered by Prime Minister Jacinda Ardern.
"The Green Party is thrilled to enter into this governing arrangement with Labour," co-leader Marama Davidson said.
The deal – which is officially called a "Cooperation Agreement" – reflects the mandate Labour received when it won its 64-seat majority in the election, Ardern said.
But, after the Greens announced it would back the deal, Ardern pointed out that it was the Labour Party which won a "clear mandate" to form a majority Government.
"I will use the mandate that we have been given."
Ardern unveiled the proposed deal in its entirety half an hour after the delegate call began – she told media it was important that the deal was made public for "transparency" reasons.
The Prime Minister also signalled that she will be looking to work with the opposition on a number of areas of cross-party cooperation, such as extending the parliamentary term and the abolishing of the "coat-tailing" rules.
The highlight of the deal is the portfolios co-leaders James Shaw and Marama Davidson would hold outside Cabinet.
Davidson will become the Minister for the Prevention of Family and Sexual Violence and Associate Minister of Housing (Homelessness).
Shaw will be the Minister of Climate Change and Associate Minister for the Environment (Biodiversity).
Climate Change is a portfolio he held in the previous Government and is an area he knows "inside out", Ardern said.
The Greens will also have the chairmanship of a Select Committee – which one would be decided at a later date.
Ardern said that she didn't consider offering the Greens a coalition agreement – similar to the one Labour offered NZ First after the 2017 election.
"Ultimately the proposed Cooperation Agreement reflects yet another evolution in our system of MMP," she said.
In total, 136 Green Party delegates voted on the deal.
Some 114 voted for, 17 voted against and five did not vote – that means the majority was 84 per cent.
At its essence, the deal means the Greens have committed to supporting Labour to provide stable Government for this term of Parliament.
The deal said: "The Green Party agrees to support the Labour Government by not opposing votes on matters of confidence and supply for the full term of this Parliament."
That means they are not allowed to vote against the Government when passing the budget.
They are, however, allowed to abstain from a vote such as that.
"This has the effect of strengthening the Government's stability and will ensure there is always a strong majority in Parliament on the most important votes," Ardern said.
As well as the ministerial posts, Labour has promised to work with the Greens in a number of "areas of cooperation".
This includes achieving the purpose and goals of the Zero Carbon Act, protecting our environment and biodiversity and improving child wellbeing.
"This [deal] will provide New Zealanders with the certainty of a strong, stable Labour Government with support from the Green Party over the next three years," Ardern said.
Ardern said Shaw and Davidson have "very clearly defined" areas that they will be working on if the deal was approved.
"We have had three years working together," she said of the Greens over the past three years.
"We both have a win-win from this arrangement."
The official agreement will be signed in Ardern's Beehive office on Sunday.
Looking ahead, Ardern will name her new Cabinet on Monday and ministers will be sworn in on Friday afternoon.