One £45m contract covers external structural work to the station and the grade I-listed train shed, and the construction of a train deck and international passenger concourse.
The interior design and fit-out contract is valued at £30m, and the M&E contract, which covers services and passenger information systems, is worth £35m.
Interested companies will be asked to a presentation by Union Railways (North), a subsidiary of London and Continental Railways, at the end of this month.
Invitations to tender will be issued to about five contractors in February next year, with contracts to be awarded by next December.
An in-house architect from joint venture Rail Link Engineering, will carry out the design.
The contract details have been advertised in the European Union's Official Journal.
The project is one of three major redevelopment schemes in the area. Costain has teamed up with Taylor Woodrow for the redevelopment of King's Cross Tube station. Developers Argent and St George were also picked to oversee the £1.5bn redevelopment of the area surrounding King's Cross train station earlier this year.