Secretary of State for Transport Chris Grayling has given the go-ahead for a new twin-road tunnel beneath the River Thames.
The Silvertown Tunnel will link the Royal Docks with the Greenwich Peninsula, and will cut congestion and ease pressure on the Blackwall Tunnel, says Transport for London.
Mayor of London Sadiq Khan said he was "delighted".
Green Party London Assembly member Caroline Russell accused transport authorities of "ignoring our fears over worsening London's terrible air pollution".
"New roads attract new traffic, pollute the air and are incredibly expensive… Londoners need healthy streets where they can trust the air they breathe."
The No to Silvertown Tunnel campaign group said the approval "sends a terrible message to the wider world: That London is closed to new thinking on how to deal with congestion".
Tolls are expected to be in operation when it plans to open in 2023.
