The party had defied expectations, recording a swing of about 3 per cent.

They looked to win three seats, there was also a strong chance The Greens could win more, a feat not pulled off since the 2008 ACT election.

Seats in Kurrajong and Murrumbidgee were retained.

ABC election analyst Antony Green said the Greens had picked up a seat in Yerrabi.

Surprisingly, the party's strongest swing came from south, at about 6 per cent in Brindabella. There was also a chance they could pick up another seat in Kurrajong.

ACT Greens leader Shane Rattenbury told party faithful: "2020 has been a year where there has not been a lot of good news, but tonight bucks that trend".

"Canberra has voted for a positive agenda for this city. For an agenda that is about being bold, about looking forward and about tackling the big issues that we know that are out there," he said.

He said he would be having discussions with Labor and the new candidates about whether they would take on ministry positions or move to the cross bench.

"We will reflect on that this week, we'll need to talk to our party membership thinking about whether we want to remain in the ministry or whether we go to the cross bench," Mr Rattenbury said.

"Also, really importantly in the conversations we'll have with the Labor party we prefer a really bold agenda, we have a real desire to address some of those underlying issues that have been there before COVID."

Mr Rattenbury had previously indicated he thought the Greens could win six seats at the ACT election and he again echoed those views on Saturday night, telling the crowd he thought they could possibly gain a seat in each electorate.

"I am absolutely thrilled to have new members joining us in the Assembly," he said.

Perhaps the most surprising win of the night was Yerrabi, where Antony Green had called the seat for Andrew Braddock but he remained cautious.

"I wish I had confidence in Antony Green but I am just going to wait until the end of the week," he told a cheering room.

Murrumbidgee candidate Emma Davidson credited her party's win on their policy platform. She will replace retiring Greens MLA Caroline Le Couteur.

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"It's the most ambitious policy platform I've seen the ACT Greens take to an election," she said.

Ms Davidson said she saw value in being on the cross bench, like Ms Le Couteur was.

"Seeing what Caroline has been able to do over the past four years and I have huge respect for what she has been able to achieve there and she has really demonstrated how valuable that role is," she said.

Brindabella candidate Johnathan Davis was enthusiastic in his speech to the party faithful.

"I've never been more proud to live in Tuggeranong," he said.

"They have endorsed strong progressive candidates."

As part of their election pitch, Greens policies have included a $400 million housing package, $50 million towards electric car subsidies and the party wants to stop gas connections to new suburbs from next year.

Earlier on Saturday, Mr Rattenbury steered clear of explicitly stating what policies the Greens would be unwilling to compromise on in a parliamentary agreement. But he said housing and climate change would be at the forefront