The Irish carrier's monthly passenger count increased 16% to 9.5mln against the same period a year ago, while its load factor - how full its aircraft were - rose 7% points to 92%.
Rolling annual passenger numbers to May increased 13% to 93.1mln.
Ryanair has revamped its services after facing criticism of its abrasive approach to issues such as baggage charges.
Marketing chief Kenny Jacobs said the overhaul had helped it to achieve better than expected load factors on its expanded summer schedule.
He said forthcoming improvements would include a new website, new app, new cabin interiors, new crew uniforms, improved in-flight menus, reduced fees and new digital features such as 'hold the fare' and price comparison services.