Merepark Construction has secured the £26m contract to deliver the final phase of work at the Grade II listed Lewis's building, part of the £160m Central Village development.
The Altrincham firm said the contract was awarded after a competitive tender and follows its completion of the first phase strip-out of Lewis's.
The nine-storey building will include a 126-bed Accor apartment-hotel, 72,000 sq ft of office space and additional retail and leisure units.
The Central Village scheme, stretching around Central Station from Bold St to Renshaw St, also includes a cinema, two other hotels and a multi-storey car park.
It is being brought forward by a joint venture between Merepark and the Dublin-based developer Ballymore.
Work has now started on the Accor Adagio Hotel, retail leisure and office space as well as a new open-air link which runs through the Lewis's Building and connects Renshaw Street to the development.
Scaffolding is now being erected on site in advance of external cleaning work to restore the building's façade. Work is on track for completion at the end of next year.
Merepark director Alex Moore said: "To date work has been contained within the building but it's the final phase that will see changes to the building's exterior and give the people of Liverpool a real sense of the transformation that's underway.
"This building is the linchpin for the rest of the Central Village scheme and we're delighted to be playing such an instrumental role in its refurbishment."