Derby-based Bombardier has won a £1 billion contract to supply the trains for the cross-London Crossrail project, in a big boost for UK manufacturing.
Bombardier, which has suffered contract disappointment in the past from overseas opposition, beat Japan's Hitachi and Spanish firm CAF to the lucrative contract.
A total of 65 trains will be built in Derby in a deal which will support 760 UK manufacturing jobs and 80 apprenticeships.
Rail, Maritime and Transport union general secretary Bob Crow said: "This is a fantastic and deserved result, coming after a long-running campaign led by RMT and the local community in Derby in the wake of the Thameslink fleet shambles, which will go a long way to saving the future of train building in the nation that gave the railways to the world."
Business Secretary Vince Cable said: "As well as providing a great boost to Bombardier and the Midlands this decision represents a real vote of confidence in British manufacturing, supporting 760 UK manufacturing jobs and 80 apprenticeships.
"The Government has been working hard with industry to support the UK rail supply chain to maximise growth opportunities through contracts like this.
"Our industrial strategy is giving business the confidence to invest - securing high-skilled jobs and a stronger economy."
The contract, between Transport for London and Bombardier, covers the supply, delivery and maintenance of 65 new trains and the construction of a maintenance depot at Old Oak Common in north-west London.
The depot deal will create 244 jobs and 16 apprenticeships. When fully operational it will support 80 jobs to maintain the new fleet of trains. .
London mayor Boris Johnson said: "The Crossrail project is now rolling on full-steam ahead. The manufacture of these new trains will not only revolutionise rail travel in London, they will deliver jobs and economic growth in their birthplace in Derby and across the UK.
"With a firm on board to deliver a fleet of 21st century trains and the tunnelling more than halfway complete, we're on track to deliver a truly world-class railway for the capital."
Transport Secretary Patrick McLoughlin said: "This announcement will mean state-of-the-art trains providing quick, comfortable journeys for the millions of people Crossrail will serve. It is also great news for British manufacturing and for Derbyshire.
Sir Peter Hendy, London's transport commissioner, said: "Crossrail is already generating jobs in London and the UK. When it opens it will continue to provide jobs and the growth it will bring will boost the whole economy.
"Crossrail is a fantastic example of the widespread benefits that sustained investment in transport infrastructure brings."
Each Crossrail train will be 200 metres long and able to carry up to 1,500 passengers. Key features include air conditioning and inter-connecting walk-through carriages. On-train passenger information systems will deliver real-time travel information to allow passengers to plan their onward journeys.
First mooted in the 1990s but then scrapped on cost grounds only to be revived in the last decade, Crossrail will boost London's rail-based capacity by 10%
It will run from as far west as Maidenhead in Berkshire, connecting Heathrow, and Abbey Wood in south London, and going as far east as Shenfield in Essex.
At peak times, there will be up to 24 trains an hour between Paddington in west London and Whitechapel in the City of London.
TfL will introduce the new trains from May 2017, with the fleet progressively introduced to the existing rail network well in advance of services commencing through Crossrail's central section in December 2018.
Bombardier lost out to Siemens of Germany in 2011 for a £1.6 billion contract for trains for the north-south cross-London Thameslink rail project.
The decision sparked controversy, with fears that train-making at Derby might end.
Siemens had been in the running for the Crossrail contract but pulled out last year.
Unite national officer Julia Long said: "This is great news for the workforce at Bombardier and for Derby. After the disastrous handling of the Thameslink contract this news must come as a massive relief for the skilled men and women at Bombardier.
"Bombardier will continue to build trains, valuable jobs will be secured and young people will have a future in manufacturing through apprenticeships. This decision is a tribute to the skills and dedication of the Derbyshire workforce."
Prime Minister David Cameron tweeted: "Great news for @bombardier and Derby with the £1billion Crossrail deal. Our #LongTermEconomicPlan means more jobs, security and opportunity."