Its results for the three months to 31 December show it outpaced rival easyJet, which last week revealed its passenger numbers for the same quarter rose 4 per cent to 15.1 million.
Ryanair added 2.5 million customers to reach 20.8 million, helping its revenue grow 17 per cent to €1.132bn (£852m) and swing its net profit figure from a €35m (£26m) loss to a €49m (£37m) profit.
Michael O’Leary, the chief executive, said: "These strong results confirm that our ‘Always Getting Better’ customer programme and our expanded business schedules, coupled with our substantial fare and cost advantage over competitor airlines is drawing millions of new customers to Ryanair."
Ryanair said it was expecting to become the first EU airline ever to carry more than 100 million customers in a single year, in "2015/2016".
It will be reinforcing its low fares positioning with a number of events and special promotional fares celebrating its 30th birthday, which it dubbed "the 30th birthday of low fares in Europe".
The anniversary of Ryanair’s first flight, from Waterford in Ireland to London Gatwick, is in May.
However, it sought to temper expectations that its profits would dramatically improve on the back of the recent plunge in the oil price.
It said it expected increased price competition from rival airlines, which had not hedged their fuel costs, in the short-term because its fuel is currently hedged at $92 per barrel. In the longer term it said it expected to pass on the drop in price to its customers.
"As lower oil prices kick in over the next two years, Ryanair intends to pass on much, if not all, of these savings to our rapidly growing customer base in the form of lower fares and therefore our profit growth expectations will be modest in FY16."
The company is also expecting to deliver a big upgrade to its mobile app in April.
Today’s results come a year after the airline’s new-found commitment to customer service saw it appoint its first chief marketing officer, Kenny Jacobs.