Sadiq Khan is planning to give residents a ballot on whether estate regeneration projects should go ahead.
Under the proposal, the mayor would only provide funding to schemes involving demolition if the project is supported by residents in a ballot.
Khan says the plan, which is part of his "Good Practice Guide to Estate Regeneration", will protect London's social housing and "empower tenants, leaseholders and freeholders".
London Assembly member Andrew Boff said:“In almost two years as Mayor, Sadiq Khan has consistently flip-flopped on this issue and refused to be drawn.
“The fact he’s finally settled on a position in favour just weeks before his potential re-selection smacks of pure cynicism and self-interest."
The news come after Caire Kober, the Labour leader of Haringey council, resigned over opposition to the council's proposed public-private partnership with LendLease. The Haringey Development Vehicle would provide thousands of homes for the area, but its future is in question after Labour's left-wing campaign group, Momentum, pressured Kober to drop the scheme.
Labour leader Jeremy Corbyn said: "Regeneration must put local people first, not property speculators. Too often these large projects have led to social cleansing, jacking up of rents and communities broken apart.
"Labour is committed to giving residents the right to a ballot across the country so that when we're in government we can deliver real regeneration for the many not the few."