A £2.7billion deal has been struck to build a fleet of trains which will help cut journey times from Aberdeen and Inverness to London.
Transport Secretary Patrick McLoughlin confirmed that almost 500 carriages to run on the line will be manufactured in County Durham.
The Class 800 trains will start operating on the route, which runs south from Edinburgh, in 2018.
They are expected to cut journey times to London by 15 minutes and improve reliability.
There will be 19% more seats on each train.
Mr McLoughlin said: “We are building a world-class rail system and the Intercity Express programme is a key part of that.
“These new trains will transform rail travel between many of the great towns and cities of England and Scotland.”
Scotland Office Minister David Mundell said: “This is a phenomenal investment in one of Scotland’s key rail networks.”
The contract to deliver the carriages has been agreed with Agility Trains, a consortium of Hitachi Rail Europe and John Laing.
A total of 866 carriages will be manufactured at Newton Aycliffe for use on the East Coast and Great Western main lines, creating 730 jobs.
In addition to the 497 carriages confirmed for the East Coast line, a further 369 carriages will be used on the Great Western line from 2017.
The Hitachi-led consortium, Agility Trains, was named as the preferred bidder for the contract in February 2009, during the last Labour government, but a final deal has been beset by delays.
The UK Government is controversially moving to re-privatise the East Coast main line, which has been in public ownership since November 2009, when National Express pulled out.