Virgin Trains East Coast is investing £21 million in refurbishing its entire fleet.
The interior of each of the group's 45 trains will be completely renovated, with the first entering service on December 14 on Virgin's new Sunderland-London service.
The work will overhaul 401 carriages and will see the replacement of 24,123 seats, with leather seats fitted in first class, refurbished toilets, and new carpets and curtains.
Virgin said it has "committed more than £40 million to improving its train fleet since it launched its east coast franchise in March, as part of its plans to invest £140 million over eight years".
It is also fitting 35 new engines to its diesel High Speed Train fleet.
David Horne, Virgin Trains' managing director on the east coast route, said: "This multi-million investment in our trains [is] not only one of the biggest investments of its kind ever seen on the east coast route, but also three years ahead of the introduction of new Super Express Trains as part of the government's Intercity Express programme.
"We're investing now so our customers can benefit from new seats and a great new on-board environment before we get a new fleet of 65 trains from 2018."
Last month, Scotland's First Minister Nicola Sturgeon unveiled the new Virgin Trains livery for the Flying Scotsman (see news, October 29).
Graham Smith