The app will update station staff on where a passenger is at any point, useful in the event of a delay, change of platform or missed train.
Four rail companies are using an early version, with the full one to be available across Britain next autumn.
Paralympian Anne Wafula-Strike said the app would “empower disabled people to travel without any fear”.
Currently when passengers with mobility problems book assistance, a print-out is given to station staff in the morning.
But when a change occurs there is no way to update the paper list, which can lead to staff being in the wrong place and causing some passengers requiring help to go without assistance at all.
The app, developed by Transreport for the railway industry, will allow users to create a profile, amend and cancel bookings and give staff live information to accommodate short-notice changes.