The Peckham Coal Line which will become a new urban park.
Peckham Coal Line designer Nick Woodford said: "The Coal Line is a way of connecting people, whether that be traders benefitting from greater numbers of visitors, or creating and building on networks of local community groups.
"Peckham has a heritage of grassroots activism, in influencing planning projects and turning disused spaces into cultural destinations.
"We see the Coal Line as part of this tradition."
The Mayor’s funding will contribute to a full feasibility study examining how the Coal Line will be built, any planning issues involved and build costs, as well as speaking to residents, businesses schools and commuters in further workshops.
The remainder of the required funding will be raised through crowdfunding website Spacehive.
Johnson said: "The Peckham Coal Line project is a fantastic example of how we can harness the enthusiasm of civic crowdfunding and work more directly with Londoners to improve their neighbourhoods."
"I urge you to go online and help your local project reach their total."