Barratt Developments has bought two sites in Southwark and revealed plans for the construction of "more than 1,000 homes" on them.
It said the sites in Blackfriars Road and Surrey Quays’ Cannon Wharf had a gross development value of £400 million.
According to Barratt, the Cannon Wharf site will contain 679 homes - of which 562 will be private, and some 71,000 sq feet of commercial and retail floorspace.
It currently houses a business centre, open-sided warehouses, and a large car park.
The Blackfriars Road scheme will have some 400 homes, in a mix of tenures.
Chief executive Mark Clare said the Southwark acquisitions underscored its confidence in the capital’s housing market.
"We are delighted to have secured these high profile projects within London,” he said.
“Barratt has a strong track record of delivering in London and our capability to design, build and sell large complex schemes is giving us a competitive advantage in the capital.
“Our London portfolio is expanding fast - we now have over 3,000 units under construction on 22 sites across 17 boroughs providing homes ranging from £145,000 to £5 million.
“Our business in London continues to perform especially well and pricing remains robust."
"We've already surpassed one degree of global warming," said Kristen Buida, manager of the London Climate Change Partnership.