More than 900 jobs will be created as part of a £4.5bn contract to build and maintain new inter-city trains, the Department for Transport has said.
Agility Trains - made up of Japanese firm Hitachi and UK company John Laing - will construct a new factory in Newton Aycliffe, County Durham.
New maintenance depots will be built in Bristol, Swansea and Doncaster.
The government has been in negotiations about the details since Agility was made the preferred bidder in 2009.
The 92 new trains trains will replace the ageing Intercity 125 trains and will run on the East Coast main line in 2018 and Great Western main line in 2017.
As well as 200 people employed in the construction of Hitachi's new train assembly plant in Newton Aycliffe and the 730 skilled staff who will work there, the deal will also secure thousands of jobs in the supply chain, the government said.
"We are absolutely delighted to have achieved contract award on the Intercity Express Programme," said Agility Trains chief executive Alistair Dormer.
"It is among the biggest contracts ever closed in the UK rail industry and will mean a step change in reliability, capacity and comfort to British passengers."
Leader of Durham County Council, Simon Henig, said: "This is a hugely significant moment for County Durham. Rail manufacturing is coming home, returning to where it all began and to the people who played such a key role in its history.
"It gives me great pleasure to know that hundreds, perhaps thousands, of our younger residents in particular now have fresh hope for careers in manufacturing and engineering for the foreseeable future.
"Hitachi has today played an important role in ensuring the world is looking at our county and we will make the most of this fantastic opportunity."
The RMT rail union, however, was critical of some parts of the deal.
General secretary Bob Crow said: "While any new jobs are welcome, this whole botched and delayed intercity replacement programme could have generated thousands of skilled manufacturing jobs if the trains had been built from scratch in the UK rather than just assembled in kit form shipped from Japan."
However, a passenger group said it should be good news for those using the trains.
"The new trains, coupled with last week's news about electrification, should not only mean new, faster trains, but also more seating," said Anthony Smith, of Passenger Focus.
"Attention will now shift to the internal layout of the new trains. This will dictate the amount of space for passengers and their luggage."
The confirmation of the final details of the contract was made a day before the Global Investment Conference in London, one of a series of trade and investment events coinciding with the Olympic Games.
Jaguar Landrover said earlier that it was creating 1,100 jobs at its Castle Bromwich plant to build new models.
The government was criticised last year for awarding a contract to build new train carriages for its Thameslink route to a consortium led by German firm Siemens.
The decision not to award it to Canadian firm Bombardier was blamed for the loss of more than 1,000 jobs at its UK factory in Derby.
It had been feared that the decision would lead to the complete closure of the plant, the UK's only major train-making facility, but its owners said earlier this year that it would remain open for the time being.