Ryanair carried 7.5 million passengers in December, a 25% rise on the previous year.
Load factor rose 3 percentage points to 91%, and rolling annual traffic grew 17% to 101.4 million.
"On the back of lower fares in December, following the terrorist events in Paris and Brussels, Ryanair’s monthly traffic grew by 25% to 7.5m customers, while our load factor jumped 3% points to 91%," said Kenny Jacobs.
"Our traffic growth over the past two years has been remarkable, rising by 50% over our December 2013 traffic figure of 5m."
The December figures meant Ryanair carried a total of 101 million international passengers in 2015.
Meanwhile, rival easyJet reported a smaller increase of 4.6% in passenger numbers to 4.8 million and load factor dipped by 1.8ppt to 86.6%.
It blamed the fall on the Paris attacks.
"EasyJet is France’s second largest airline and around 23% of the airline’s capacity ‘during December was on French touching routes."
It said load factors are now recovering to normal levels and management ‘do not anticipate any change to full year market expectations’.
