Plans for blocks of flats and a three-storey stadium for Cray Wanderers Football Club in Flamingo Park, Chislehurst, were initially approved by Bromley Council, however the mayor has now rejected them following concerns over the protection of green space and that the plans included no affordable homes.
In a statement, Mr Khan said: “I am determined to oppose building on the green belt, which is now even more important than when it was created.
“Working with my planning team, I will continue to use my full range of planning powers to further strengthen protections for open and green spaces in the London plan and ensure we are making the most of brownfield sites across the city, including the vast swathes of public land which are ripe for building homes for Londoners.”
Two four-storey residential blocks of 28 flats, 393 overground car-parking spaces and community sports pitches were also included in the plans.
Despite rejecting the Flamingo Park development, the statement insisted that the mayor had also consented to a number of housing schemes across the capital.
Earlier this month, the mayor backed the demolition of Soho’s historic former Foyles building to make room for a mixed-use scheme, despite protests from three historic conservation groups.
Mr Khan has also revealed plans to change permitted development rights in order to protect and expand office space for small businesses.
He added: “I want to work with developers to build the homes London so desperately needs and I will be the first mayor to use my planning powers to much greater effect, supporting boroughs rather than hindering them, and getting a firm grip on the housing crisis.”