Joined by MPs, councillors and candidates from Labor, Greens and independent ranks on Wednesday, Cr Moore claimed that proposed changes to voting for the City of Sydney council represented "a very sorry day for our city".

The proposed changes would make it mandatory for businesses to vote and would give businesses double the voting power of residents.

There has been speculation that Cr Moore, 68, would bow out at the 2016 council poll, ending what would by then have been a 12-year stint in the mayoral robes.

She said the bill introduced by the Shooters and Fishers Party, and backed by the NSW government, was "a real assault on democracy".

"[The council is] competent, we are effective, we are progressive and we are corruption free. That is not a boast that this government can make," she said.

"We will fight this. When they commit these bastard acts, it makes you want to fight … harder."

Asked if that meant she would recontest the mayoralty, she said "It's this sort of thing that makes me want to," before adding: "Who knows what will happen in two years?"

Should the changes come into effect, and Cr Moore does not recontest, it would be a major blow to the council's progressive agenda, which includes measures such as bike lanes and climate change action.

The changes could flood the election with Liberal-leaning business votes, eroding the influence of the progressive Cr Moore.

The bill passed the NSW upper house on Wednesday. The government proposed only minor amendments, and supported the double business vote.

The government had signalled that business voting rights could be expanded in council areas with large economic centres such as North Sydney, Newcastle and Wollongong. However, the Greens successfully moved a motion that would prevent the changes being applied to other council areas.

Greens MP David Shoebridge said the amendment would come as a "relief" to the state's 151 other councils.

"This bill has almost no friends in NSW. It's rejected by local government, it is rejected by mayors and councillors and residents across the state," he said.

"Today is a dark day for democracy … the government has no mandate to deliver this change in the City of Sydney, which has a popularly elected lord mayor who they just don't like."

The government and the Shooters and Fishers Party say the changes will ensure businesses are better represented on the council.

The NSW Parliament's legislation review committee has expressed concern that business voters "may be granted a disproportionate influence on the election".

An independent review of a similar voting system in the City of Melbourne has recommended that businesses revert to having only one vote.

In Parliament on Wednesday, Local Government Minister Paul Toole said the changes were "about democracy [and] transparency" and would give businesses "a voice in their community".