The 137-seat Class 158 trains will also be fitted with new CCTV systems and automated passenger-counting systems.
The first carriage will be on the track ready for the opening day of the new Borders Railway at the weekend.
The revamped trains will be rolled out at a rate of about one a month until April 2018 on routes across Scotland.
The routes include:
Transport minister Derek Mackay said refurbished trains would further improve the travel experience.
He said: "Passengers will soon see more of these refurbished trains rolling out on routes all over Scotland and, fittingly, the first carriages off the production line will start their journey as part of the historic Borders Railway launch, with all the benefits that will bring for the Borders, Midlothian and Edinburgh economy."
ScotRail Alliance managing director Phil Verster said: "We've listened to customers and that feedback is reflected in the upgrades being made.
"Seats are better aligned alongside windows, interiors are brighter and more modern, and people can charge phones and laptops during their journeys."
ScotRail has unveiled the first of 40 new-look trains which have improved seating, better lighting and power sockets for customers to use.