The Greens minister in the ACT government employs staff who have ethical objections to horse racing.

Instead, an ''ice-cream party'' was held to celebrate the first anniversary of Mr Rattenbury's appointment to cabinet under a parliamentary agreement with Labor.

The agreement made Mr Rattenbury, pictured, Canberra's de facto ''lord mayor'' as Minister for Territory and Municipal Services.

He also holds the corrections, Aboriginal and Torres Strait Islander affairs and ageing portfolios.

Mr Rattenbury said his first year as a minister had been productive but he acknowledged it was not clear to what extent he had maintained a distinct public identity as a Green while working in coalition with Labor.

''I think the Greens membership are very upbeat,'' he said.

''They're really pleased to see a Green having a day-to-day input into the running of government.

''But in the broader community, it is a bit unclear to me as to whether people are seeing a Greens minister and four Labor ministers or whether they're just seeing the government

''To be honest, I don't think people are that engaged in ACT politics in the sense that they're sitting there thinking about the niceties of that. They just want to see people making stuff happen''

While one of his biggest challenges has been running the Corrections portfolio, Mr Rattenbury said his proudest achievement was seeing progress on the Capital Metro light rail system, which was part of the Labor-Greens agreement.

''This will be the project that will have a lasting impact on Canberra for decades to come,'' he said.

''And to have been able to trigger the political commitment to building that infrastructure is something the Greens have campaigned for a long time.''

One of Mr Rattenbury's greatest frustrations was a reluctance by the Liberal Party to work with him. ''Last term, as the Greens on the crossbench, we were able to work with the Liberal Party, have conversations, get things done,'' he said.

''But because I'm now part of the government, they perceive me as part of that enemy bloc so therefore aren't open to that relationship that was possible last term.''

While he occasionally voted against Labor in the Assembly, Mr Rattenbury said he had good working relationships with Chief Minster Katy Gallagher and his other ministerial colleagues.

''I talk with the Chief Minister regularly and we try and identify things that might come up and start to find ways to work through them before they become a significant dispute,'' he said.