The tunnel is planned to be built between Greenwich Peninsula and Silvertown in the historic Royal Docks near City Airport.
Transport for London will begin preliminary consultation work on the proposed Silvertown tunnel in February, said the mayor last night at a meeting of local Government leaders.
The “Boris” tunnel will follow a similar line to the cable car from North Greenwich to the Royal Docks currently under construction and will relieve pressure on existing tunnels at Blackwall and Rotherhithe.
Johnson also announced he was pushing ahead with an extension of the London Underground Northern Line to Battersea, despite the collapse of plans to redevelop the derelict power station.
The announcement follows the Chancellor’s autumn statement which said the Government would work with the Mayor of London and Transport for London to explore options for proposed additional river crossings.