Demolition work at Rathbone Place, W1 is scheduled to start in February ahead of main construction to transform the 2.3 acre site at the east end of Oxford Street.
The site was formerly occupied as a sorting office by the Royal Mail Group who left in August.
Great Portland Estates paid £120m for the site in 2011 and leased it back to the Royal Mail.
Architects MAKE have drawn-up designs to provide new buildings totalling 414,000 sq ft, which will include a new public square and new pedestrian routes linking Rathbone Place and Newman Street together with 42,000 sq ft of retail space, 217,000 sq ft of offices and 155,000 sq ft of residential in 162 flats.
The scheme is believed to have a development value of around £500m.
Neil Thompson, GPE Portfolio Director said “We are delighted to have received support for our scheme from Westminster, with whom we have worked very closely over the last two years.
“Rathbone Place will be one of the West End’s most exciting new developments and is one of several projects GPE are working on for delivery over the next few years”.