Lord mayor Nuatali Nelmes says ratepayers "absolutely" support Newcastle council's move to new offices in Newcastle West.
Removalists have been shifting furniture, equipment and documents out of the council's City Administration Centre "roundhouse" this week and into the rented building in Stewart Avenue.
The bulk of about 450 staff will move into the new offices on Tuesday.
Councillors will continue meeting at City Hall this year while a new chamber is being installed on the new building's ground floor, scheduled to open in February.
The shift to new premises has attracted criticism from the Newcastle Independents alliance, Cr Nelmes' political rivals in the council chamber.
This is in relative terms quite a frugal exercise at the City of Newcastle in terms of cost control for moving staff into a new building.Lord mayor Nuatali Nelmes
The council has refused to make public the costs of the move, but contracts for the new office's design and fit-out exceed $10 million.
The council will also pay about $36 million in rent over the initial 15 years of the Stewart Avenue lease.
It has sold the CAC to developer Ghassan Aboud for $16.5 million and put the Fred Ash building and two adjacent council administration buildings on the market.
It has spent $12.5 million restoring City Hall's clock tower and sandstone facade since 2015.
Chief executive officer Jeremy Bath asked the new building's owner to add a sixth floor soon after signing the lease in late 2017.
It later emerged this floor would include executive suites for Mr Bath and Cr Nelmes.
Cr Nelmes defended the move in an interview with the Newcastle Herald this week, arguing it compared well financially with other councils shifting premises.
"This is in relative terms quite a frugal exercise at the City of Newcastle in terms of cost control for moving staff into a new building," she said.
"When I look at the costs that have been incurred by other councils, you're looking at a minimum $30 million to build new buildings, to move staff in.
"Maitland, I believe, are building a whole new building for around $35 million."
Maitland City Council has embarked on a $43 million overhaul of its civic precinct, including a new $28 million administration building, $9.4 million Town Hall upgrade and $5.6 million car park and "site improvements".
The project, scheduled for completion in late 2021, is being funded by a loan.
Cr Nelmes said City of Newcastle's new building would help attract and retain staff and the costs involved were "very similar if we would have had to renovate the roundhouse in the city".
"Given the age of that building and the money being spent on it to make it fit for purpose as a hotel, it's tens of millions of dollars," she said.