He said holidaymakers should brace for prices to rise by a “high single-digit per cent” over the peak season as demand for breaks on European beach resorts rebounds thanks to the lifting of pandemic travel restrictions.
The budget airline’s chief executive also said there were likely to be ongoing delays at airports, blaming staff shortages.
He added he hoped to see the worst of the delays ease off in time for the busy summer season, but stressed it would still be a “challenge” for passengers getting through UK airports.
The comments came as Ryanair reported annual underlying losses narrowing to €355 million (£302 million) and said it hopes to return to “reasonable profitability” in the current financial year.
But it cautioned that despite a bounce back in passengers and bookings, the recovery “remains fragile”.
Mr O’Leary’s comments mark the latest pricing alert ahead of the peak season, after holiday giant Tui last week said it would not be offering last-minute, low-price deals this summer due to a recovery in customer demand.
Ryanair signalled prices would ramp up over the next few months in the sector due to a cut of about 15% in European flight programmes across the sector over the summer.
Mr O’Leary revealed that news of Russia’s invasion of Ukraine cost it around one million bookings at the end of February and the beginning of March.