Other airlines have made similar moves amid concerns that Brexit could severely disrupt air traffic between Britain and continental Europe.
"Ryanair today confirmed that a subsidiary company, Ryanair UK, filed an application on 21 December for an Air Operator's Certificate (AOC) with the Civil Aviation Authority in the UK," a spokesman for the airline said.
"This may be required for Ryanair's three UK domestic routes in the event of a hard Brexit in March 2019."
In October, Hungarian budget airline Wizz Air announced that it too was establishing a British division, Wizz Air UK, to make its operations "Brexit ready".
In July, British low-cost airline easyJet established a Vienna-based division to allow it to keep flying across the EU amid any Brexit fallout.
Source: AFP