Taylor Wimpey Central London has bought a 94,000 sq ft site in Lambeth, SE11.
The boutique arm of the housebuilding giant has exchanged contracts on the former headquarters of the Royal Pharmaceutical Society at 1 Lambeth High Street.
The site was brought to market with an asking price of £25m.
The 0.38-acre freehold site, named Palace View, has existing planning consent to redevelop a 1970s office building into a mixed-use scheme of 55 flats and 14 affordable homes.
There is also current planning permission for 7,900 sq ft of retail and office space.
Ingrid Skinner, managing director of Taylor Wimpey Central London, said: “Building on our reputation for agility in the marketplace, the exchange of 1 Lambeth High Street was finalised within just two weeks and we intend to maintain this momentum by starting on site as soon as possible after the completion of the sale.
“The anticipated delivery of the development is late 2017.”