It will mean an additional 1750 seats a day will be provided on the extra Virgin Trains services on the West Coast Main Line.
The new daily total of 15 Pendolino tilting trains each way represents a doubling of the number of weekday services between Glasgow Central and London Euston since 1997.
Karen Hattie, general manager for Virgin Trains in Scotland and Cumbria, said: "Overall passenger numbers have more than doubled on our routes."
Departures from Glasgow Central will be one an hour from 5.40am to 6.40pm after an initial train at 4.28am.
Currently, there are gaps of two hours without London-bound trains after the departures at 2.40pm and 4.40pm.