Four round trips will be complete with carol singers and elves.
Good boys and girls from across the midlands will have the opportunity to ride the Christmas Express with Santa and Mrs Claus.
The trains will depart from Mullingar station to Longford and back, two on Saturday and another two on Sunday.
Passengers will be treated to hot chocolate on the platform and entertainment from carol singers, face-painters, and even a few elves.
Each train will also have a sensory-friendly carriage for a quieter experience for anyone with sensory issues.
Group leader with the Milltownpass 9th Westmeath Scout Group, and a worker with Irish Rail, Fiona O' Shea says a team of volunteers and support from Irish Rail have made the event possible: