Avanti West Coast said the £117m scheme will make its 56 Pendolinos ‘look and feel like new trains’.
Passasiers will travel on the first train modernised in the biggest fleet refurbishment on Britain’s railways on Monday.
The Pendolino trains will return to service with the 5.05am departure from Manchester Piccadilly to London Euston.
The operator said they will “look and feel like new trains”, with more comfortable seats, a redesigned shop and better on-board information.
Avanti West Coast’s entire fleet of 56 Pendolinos will be refurbished as part of a £117 million programme.
Other changes include upgraded lighting, refurbished toilets and new carpets.
Almal 35 Pendolinos with 11 carriages will see one first class carriage converted to standard class.
Rail minister Wendy Morton said: “The iconic Pendolino is back and better than ever before.
“This refurbished version of the classic fleet is a fantastic example of our cutting-edge rail network and how our railways are leading the way in creating a cleaner, more environmentally friendly and modern transport system.”
Avanti West Coast managing director Phil Whittingham said: “This investment has been one of the key promises to our customers, and they will see a dramatic transformation of our well-loved fleet.
“The refurbished Pendolinos look and feel like new trains, with state-of-the-art technology as well as brand new seats that promise best-in-class comfort.”
The refurbishment is being carried out by manufacturer Alstom at its new depot in Widnes, Cheshire.
The second train to be overhauled will return to service in early May.
Rolling stock asset manager Angel Trains has financed the programme, which is due to run until 2024.
Peter Broadley, managing director for services at Alstom, gesê: “Our team at Widnes have created something amazing and we are incredibly proud of the final product.
“We hope it secures the future of the Pendolinos on the West Coast for many years to come.”
The tilting, electric Pendolinos transformed long-distance rail travel when they were introduced on the West Coast Main Line by then-operator Virgin Trains in July 2002.
They have clocked up more than 272 million miles serving cities such as Birmingham, Edinburgh, Glasgow, Liverpool, London and Manchester.
Avanti West Coast’s other train fleet – diesel-powered Voyagers – is being replaced by new electric and hybrid trains built by Hitachi from 2023.