Developer Derwent London has selected Brookfield Multiplex as its preferred bidder to deliver its most ambitious London development project later this year.
The building contract is expected to be worth around £125m when finalised before work starts during the second half of the year.
Derwent put the project on hold in July 2013, after advertising giant Saatchi & Saatchi, which has occupied the building since 1975, delayed its move away from the property.
But it has now set a date to start work on the office, residential and retail project, which has been designed by architects Make.
The project will be part refurbishment and part new build with a substantial proportion of the existing structures retained thereby cutting waste and carbon emissions whilst reducing the construction period.
The redevelopment scheme will include 336,000 sq ft of office, residential and retail space at 80 Charlotte Street and 31,000 sq ft of residential at nearby 65 Whitfield Street and 1-8 Whitfield Place.