In March, the council detailed a proposal to sell a collection of council-owned properties on Devonport Rd to a developer, which would construct an office building the council would lease for its staff.
It was considered a medium-term solution to get the bulk of the council's workforce - currently split between three office buildings - under one roof.
The new build is expected to create significant efficiency savings and make it easier for community members to access the services they need.
Commission chairwoman Anne Tolley said in a statement the new council headquarters would activate a different part of the CBD and add to positive momentum generated by the planned civic precinct developments.
The civic project is expected to begin with the construction of a new library and community hub on the corner of Willow St and Wharf St in late-2022.
Tolley said both parties to the lease reached an agreement that allowed them to minimise the impact of escalating construction costs, while still delivering high-quality, sustainable outcomes.
"We want to show leadership in our sector and make a real contribution to reducing carbon-induced climate change through this project," she said.
"We have some defined sustainability targets for this building and we're looking forward to finalising those in the new year."
Willis Bond managing director Mark McGuinness said the company was "delighted to partner with Tauranga City Council to help reposition their team in the heart of the CBD, and utilise a forward-thinking and responsible approach to design and construction".
In 2014, about 330 of the council's 520 staff were moved after tests confirmed the presence of toxic black mould and Chrysosporium fungi on its first floor, which has since been sealed off.
In recent years, clusters of staff have been relocated to office spaces on Devonport Rd, Spring St and more recently Cameron Rd.
