Wandsworth will receive £40m towards building affordable housing from a property investor taking part in the major regeneration of Nine Elms.
A prior agreement between Wandsworth Council and developer Ballymore means Wandsworth is entitled to a share of revenue on the Embassy Gardens scheme if values increase beyond a set benchmark.
Ballymore has agreed to make the maximum £40m payment, to be collected by the authority in stages.
The windfall will come on top of the affordable housing already being delivered at Embassy Gardens and the £55m Ballymore will contribute to infrastructure in Nine Elms.
The council is in the early stages of planning 58 new affordable rent homes in Nine Elms and this money could see the programme expanded further.
Councillor Ravi Govindia, leader of Wandsworth Council, said: "Every development in Nine Elms comes with major benefits for the local community and for London.
"The Battersea Power Station scheme will see a world renowned icon rescued from dereliction and delivers more than £200m towards vital local services.
"Just over the road the New Covent Garden Market development will modernise Wandsworth’s biggest employment hub and create a new centre for London’s food industry.
"All of the developers are paying towards the Northern Line Extension which is unlocking tens of thousand of new jobs and billions in growth. The new economy taking shape in Nine Elms will support our community for generations to come."
Opposition Labour Councillor Simon Hogg welcomed the news and said it was great the council was standing up to make sure local people benefit from the scheme .
But he added: “The real problem is that the council has since changed the rules so that excess profits now all go to the developer, rather than being shared with the local community.
“If the council was serious about Nine Elms benefiting all residents, it would bring back the profit-share clauses like this one that earned £40m at Embassy Gardens.”
Ballymore’s proposals for Embassy Gardens include the redevelopment of approximately 15 acres of land surrounding the new US Embassy, with 2,000 new homes, leisure facilities and a hotel.
Everything from roads to basic utilities is being improved in the area, in anticipation of the increase numbers of people, with the combined cost expected to be around £1bn funded by the private sector.
There are 2,700 affordable properties planned across the area.