Katy Gallagher is elected as chief minister.

Katy Gallagher is elected as chief minister. Photo: Rohan Thomson

Chief Minister Katy Gallagher wants a more co-operative style of politics to be one of the hallmarks of the eighth ACT Legislative Assembly since self-government.

But Opposition Leader Zed Seselja has warned he will speak out against extreme policies and rising costs.

Ms Gallagher was re-elected Chief Minister with the support of Greens MLA Shane Rattenbury on Tuesday, when the Assembly met for the first time since the October 20 election.

Zed Seselja.

Zed Seselja. Photo: Rohan Thomson

The Chief Minister told the Assembly that, with the numbers almost tied, she hoped there would be occasions when all 17 members would work collaboratively.

''The Canberra community have elected a parliament where the numbers are 8-8-1. It's over to us now to make that parliament work,'' she said. ''It's important as we begin the eighth Assembly to acknowledge that we all start at the same point. We are all here because each of us individually loves this city, because we are all contributors, because we all want to make the city a better place to live.''

Ms Gallagher said the political system did not always have to be confrontational.

''While there are many aspects of our system of governance that are adversarial, there are also many occasions where we come together in the spirit of compromise and collaboration … and I believe there should be more of those times,'' she said.

Mr Seselja said it was disappointing that the Liberal Party had been denied government despite winning more votes at the election than any other party.

''I must express disappointment that this is the first time in territory history that the party with the most votes doesn't have the chance to form government,'' he said.

''We accept the process that was undertaken … but that does not mean that we agree with the result.''

Mr Seselja promised to hold the government to account.

''Winning the popular vote but being denied government means we have more responsibility than ever to stand up for Canberrans who have been denied this outcome,'' he said.

''More than ever we need to keep an eye on costs, something the electorate clearly voted against.

''More than ever we will stand up against policy that will push us to extremes, something the electorate emphatically voted against.''

Mr Rattenbury said he was looking forward to serving in the Labor cabinet. ''It is time for us to play a role in government,'' he said. ''I'll look forward to playing my part in a cabinet team to deliver a fairer and more sustainable future for our city.''

Mr Rattenbury voted with the opposition to install Liberal Vicki Dunne as Speaker. Labor MLA Mary Porter will be Deputy Speaker.