The Corporation of London has completed two days of meetings to announce a deal struck between it and the Government for up to £400M in funding - the last piece of cash needed to start the project.
In a statement, "At a special meeting held this afternoon at the Guildhall, the City of London's Court of Common Council voted, after lengthy discussion, to support a financial contribution to Crossrail.
"Further announcements on a full Crossrail funding package will be made by the Government in due course," read a statement.
Crossrail will now be the crown jewels in the Government's Comprehensive Spending Review, expected next week.
Described by secretary of state for transport Ruth Kelly as, "The largest construction project in the northern hemisphere," Crossrail will finally get the green-light, following almost three decades of discussions and debates.
Running from Maidenhead and Heathrow in the west, through central London, to Shenfield and Abbey Wood in the east, Crossrail will provide up to 24 trains an hour in peak time.
Crossrail's hybrid bill is currently working its way through Parliament, due for Royal Assent towards the end of this year.
The project will begin work in 2010, to complete in 2017.