Legal &General has forward-purchased 265,000 sq ft of commercial space at the International Quarter, the £2.3bn ($3.35bn) development at Stratford, which is one of the largest commercial developments in London at four million square feet.
The Transport for London (TfL) building - which is in the early stages of construction - will stand at the gateway to Queen Elizabeth Olympic Park and will house 3,000 TfL employees from autumn 2017.
In acquiring the building, Legal & General will make staged payments over the course of the development period up to a total consideration of about £245m.
Lendlease, an international property and infrastructure group listed on the Australian Stock Exchange, and LCR, wholly owned by the UK government's Department for Transport, will continue to manage the delivery of the building through the Stratford City Business District joint venture.
The Financial Conduct Authority (FCA) has also committed to 425,000 sq ft of space at the International Quarter for its headquarters in 2018.
"A significant new growth area for London, it is anticipated that Stratford will benefit from the creation of more than 40,000 new jobs and 11,000 new homes in the coming years," Gordon Aitchison, director of Investment and development at Legal & General Property, said. "Stratford is already one of the busiest transport hubs in the capital and the property forms the first exciting phase of Lendlease's and LCR's International Quarter development, which will eventually provide 4m sq ft of office accommodation."