The government is "committing the funding required" to begin tunnelling work to bring HS2 to London Euston station, Chancellor Rachel Reeves has announced.
Ms Reeves said in her Budget speech this would encourage private investment in the area.
In October last year, then-prime minister Rishi Sunak announced that extending the high speed rail project from Old Oak Common, in the suburbs of west London, to Euston, near the centre of the capital, was reliant on private investment.
This was aimed at saving £6.5bn of taxpayers' money.
Major HS2 construction work at a site alongside the existing Euston station has been halted since the previous March due to funding doubts.
Ms Reeves said: "We are committing the funding required to begin tunnelling work to London Euston station.
"This will catalyse private investment into the local area, delivering jobs and growth."
The Commons Public Accounts Committee issued a report in February stating it was "highly sceptical" that the Department for Transport would be able to attract private investment on "the scale and speed required" to make extending HS2 to Euston "a success".