Sadiq Khan could move City Hall out of its current location in Southwark to east London in a bid to save £55m over five years.
Under the proposals, the Greater London Authority would leave the current City Hall building in Bermondsey, and move to The Crystal building in the Royal Docks.
Mr Khan said he believed rent on the building, by Potters Fields Park, was above market values, forcing taxpayers to hand over £11.1m a year in rent to Kuwaiti-owned private landlords, St Martin’s.
London’s local government has been based in the building since 2002.
In contrast, The Crystal building is already owned by the GLA.
The GLA faces a budget shortfall of nearly £500m over two years because of a loss of council tax and business rates income during Covid.
“My first priority will always be to protect funding for front-line services, including public transport, the Met Police and the London Fire Brigade,” said Mr Khan.
“Leaving our current home would save £55 million over five years, which would help us to protect and invest in the things that matter most to Londoners, as well as supporting the regeneration of the Royal Docks.”
The GLA will continue to lease some space in the Fire Brigade HQ on Union Street, as well as a floor from TfL’s HQ in the Palestra building by Southwark tube station.
The move would need to be signed off by September, after a process of formal consultation.
This is the first time that the GLA have had the opportunity to move, after signing a 25-year lease on the building in 2001.
The contract allows for a break clause at 20 years, which would be in December 2021. Mr Khan said under the current financial predicament it would be “negligent” for a Mayor not to consider using the clause.