Ryanair carried 11.8 million people in September, 10% more than in the same month in 2016, despite being forced to cancel thousands of flights.
The airline said 97% of its seats were filled in September, two percentage points more than a year ago.
In a statement, the airline’s spokesman Kenny Jacobs said: "These figures include the 2,100 flight cancellations announced for September and October.
"We have now refunded/re-accommodated 98% of customers who were impacted in September and October. The remaining 2% of affected customers have yet to contact us.
"We again sincerely apologise to our customers for these deeply regretted cancellations."
