A deal struck between Green and Labour council leaders saw Brighton and Hove City Council’s budget passed.
An extra £500,000 which was earmarked for the redevelopment of Brighton Town Hall will now be used for investment in “sustainability and carbon reduction”.
The compromise came after three hours of discussions and Conservative councillors leaving the chamber once the deal was announced.
Councillors voted 30 to 21 in favour of the Green proposals to change the Labour budget.
Labour leader Councillor Daniel Yates put forward the budget and said: “We have a progressive alliance delivering better things for the city.
“We need to deal with the climate emergency facing the city and create a fund for those who wish to fight climate change.
“This needs to be done, this has to be done as we also need a budget.
The money was highlighted by the Conservatives, listing improvements to George Street, graffiti removal, road crossings, parks and open spaces.
A total of £1.7 million will go towards city-wide improvements and local transport.
When the original proposal was presented by Conservatives earlier in the evening it was rejected by Labour and Green councillors.
On returning to the chamber Conservative leader Councillor Tony Janio described the situation as a Labour and Greens coalition, referring to councillors as watermelons, meaning green on the outside and red on the inside.
Green finance lead Councillor Ollie Sykes said that the Conservative proposal was used as a way to resolve the budget for Greens, Labour and Conservatives.
Green convenor Councillor Phélim Mac Cafferty said: “The Conservatives did not want to be part of the discussion.
“Now because of the climate emergency we have £500,000.”
In a statement released after the vote Councillor Mac Cafferty said: “Opposition parties are only granted six amendments to it, and we have fought hard to make sure our communities remain a priority.
“We have pushed to improve the budget being proposed– and our work will now see over £12.5 million put back into the council budget, providing serious investment into climate change mitigation, support for the homeless and challenging the plans to reduce funding for some of our most vital public services, such as substance misuse rehab and libraries.
“Once again, Greens assert that prevention is better than cure – cutting public services costs more economically, and socially, than it will ever save in the short term.
“We have shared with the city our approach, and while we cannot rescue this Labour budget, our focus on the value of prevention means that Greens make sound investments without robbing from one service to pay for another.
“Unlike the Tories, who see fit to hand down austerity year upon year, and a divided Labour who have brought forward no new ideas, it is time for a Green vision for the future of our city that puts our communities first.”