The secret deal to allow West Ham to use London's Olympic stadium is to be made public.
The mayor's London Legacy Development Corporation will be forced to disclose details of the contract following a ruling from the Information Commissioner.
West ham, Boris Johnson and the LLDC have argued 'commercial confidentiality' in their refusal to publish the contact.
West Ham contributed just £15m to the £272m cost of converting the stadium from an athletics venue to a 'multi-use arena' with a football pitch.
The club's annual rent is a closely guarded secret but it was recently revealed taxpayers would foot the bill for goalposts and corner flags. Supporters' trusts from other London clubs launched a campaign last month to demand transparency.
Lawyers for the LLDC are considering an appeal against the ruling.