Derwent London said that Crossrail had completed base infrastructure works at Soho Place and handed over the Elizabeth tube-line site to the developer.
It was the first Crossrail site to be delivered to the developer, with handover achieved almost a year before the Elizabeth line is due to open.
There is planning for a 285,000 square foot project over Tottenham Court Road station comprising 209,000 sq ft of offices, 36,000 sq ft of retail and a 40,000 sq ft theatre.
Derwent London would now start enabling works with the intention of appointing a main contractor later in 2018.
"The Elizabeth line will transform London and we are delighted that Derwent London, working alongside Crossrail, will be responsible for developing one of its most important sites at the eastern end of Oxford Street," chief executive John Burns said.
"The scheme will create a vibrant mix of office, retail and theatre use over what is expected to be one of its busiest central London stations and in a fast improving location at the heart of central London."
At 1:33pm: (LON:DLN) Derwent London share price was +37p at 3023p