The job will last until 2013 and O’Rourke will sympathetically restore the iconic Central Library and Town Hall Extension which includes works to transform St Peters Square.
Laing O’Rourke’s Construction North business was awarded the contract, the first to be tendered through the North West Construction Hub High Value Framework.
The project will generate significant work for specialist contractors, as well as creating new jobs for local people.
Construction North Leader Andrew Jackson said: “Securing this exciting and unique project will enable Laing O’Rourke to build on our solid reputation for delivering landmark projects.
“It is a complex and challenging project, and one of huge value architecturally, culturally and civically. We look forward to partnering once again with Manchester City Council.”