Muse will build offices in the centre of Colwyn Bay and redevelop an existing grade II listed civic building to the east of the town.
The first phase is expected to be worth £36m and includes a four-storey, BREEAM excellent, 95,000 sq ft office building that will replace up to 13 existing council offices.
Wes Erlam, development director at Muse Developments, said: “We’re delighted to be chosen for this exciting project which will help the Council to operate more efficiently, reduce its carbon footprint and act as a catalyst for the wider regeneration of Colwyn Bay town centre.
The new development is a key part of the Council’s wider strategy to regenerate Colwyn Bay town centre.
A public consultation will take place early next year prior to a planning application being submitted.