The Docklands Light Railway (DLR) link between Woolwich Arsenal and King George V has opened 18 months ahead of time.
The new route creates potential for residential and commercial property development, in an area previously disconnected from central London.
Announcing the extension’s official opening, Mayor of London Boris Johnson said: "I’m absolutely delighted that this extension with its cracking new station is up and running and puts Woolwich Arsenal firmly on the Tube map."
The link also connects Woolwich to City Airport and in 2012 it will help competitors in Olympic shooting events reach the Royal Artillery Barracks.
"Woolwich has long lacked the transport links that encourage the creation of new jobs, homes and shops and this is the sort of project that will help kick the credit crunch where it hurts," said Mr Johnson.
The DLR was favoured over a bus-based system, which "thankfully was deemed too unattractive for businesses to move into the redeveloping Docklands" the Open Guide to London has said.