Smoking in Sydney's second largest CBD is about to be made a whole lot harder after a ban in all public spaces was proposed.

A Sydney council hopes to establish what is possibly the nation's first smoke-free CBD in a capital city.

North Sydney councillors this week unanimously passed a motion to ban smoking in every public place in what is Sydney's second largest CBD.

Mayor Jilly Gibson hopes to eventually go even further by extending the ban across the entire municipality.

She said the latest move wasn't about punishing smokers but about improving the amenity of the area for residents, workers, visitors and school children.

"It just seems like the right time," Cr Gibson told AAP on Tuesday.

"Why not try these big ideas?

"Even if we reduce people's smoking in the CBD by, let's say, 50 per cent, that would be a huge result."

She said the world had come a long way since her school days when one of her teachers chain-smoked his way through class.

Cr Gibson said the measure goes "hand in glove" with the council's attempts to make the CBD more pedestrian friendly with hopes to move to a council-wide ban eventually.

The NSW town of Glen Innes in the Northern Tablelands introduced a smoking ban across its CBD in 2015.

Hobart City Council last week voted on a similar proposal for the Tasmanian capital's CBD.

The North Sydney proposal will now move to a community consultation period.