An estimated 150,000 passengers will use the airport over the Christmas period.
It will handle up to 120 flights each day until 25 December.
Belfast International Airport managing director, Graham Keddie, said passenger numbers were up almost 17% on the same period last year.
"We're ready for a hectic week," he said.
Mr Keddie says passengers should allow "ample time" for their journeys.
"To avoid disappointment, check what you're allowed to take on board, and also check with your airline on flight times," he said.
City of Derry Airport is also anticipating a busy time, with 10,000 passengers expected to pass through over the Christmas period.
"As well as passengers, thousands of family members are expected to descend on the airport as they welcome their loved ones home for Christmas," said Charlene Shongo, commercial and marketing manager.
She said extra staff are in place, but people flying out from the airport are encouraged to arrive "at least 90 minutes in advance of their scheduled departure time to avoid queues and possible delays over the busy holiday period".
Belfast International Airport is estimating 45,000 passengers will pass through its doors this weekend ahead of the traditional Christmas rush.