The Ireland-based airline reported profits of euro21.2m (£13.5m) in the final three months of last year.
In a statement, Ryanair's chief executive Michael O'Leary, said, "Our Web site made a very significant contribution to our growth. Internet sales are now running in excess of 65% of all bookings."
He added, "The particularly strong performance of [the Web site] contributed to an impressive 66% decline in marketing and distribution costs during a quarter when traffic grew by 39%."
A total of 3.3 million seats were sold online during the Web site's first year of trading and 300,000 bookings were taken in the first two weeks of January.
Ryanair's technology suppliers include the Ireland-based company Horizon Technology.