The civic centre hub building will span 190,000 sq ft – more than twice the size of The Beam, the first building to be constructed on the former Vaux Brewery site.
As well as the new council City Hall, it will include office space, a medical centre, a creche, a cafe/restaurant and a roof terrace.
Bowmer + Kirkland has committed to maximising the use of local subcontractors and suppliers and will host a meet the buyer event for local suppliers in the next few weeks.
Kier, Galliford Try and Vinci were among rivals looking to secure the landmark project.
Architect Faulkner Browns designed the two linked 8-storey buildings, which will be constructed on plots 13 and 14 off St Mary’s Way.
Consultant Cundall is providing structural and civils, with Desco contributing M&E design.
Construction will now get underway with the main council building due to complete by January 2021.
Once finished 1,200 council staff will move to building and work alongside a number of public sector organisations.