Aer Lingus has said it carried a total of 1.148 million passengers last month on its flights, including its regional airline operations.
This is up 2% from the 1.125 million passengers it carried the same time last year.
The airline said its "mainline" traffic rose by 3.5% in June to 1.030 million from 995,000 in June 2014.
Its long-haul passenger numbers jumped by 15.6% to 163,000 from 141, 000 in June while its short-haul passenger numbers rose by 1.5% to 867,000 from 854,000.
Aer Lingus said its load factor - how many seats it fills on each flight - inched up to 85.8% in June compared to 85.5% a year ago.
But passenger numbers on its regional services, which are operated by Stobart Air, fell by 9.2% in June to 118,000 from 130,000 the same time last year.
Meanwhile, Aer Lingus has announced a new route from Cork to Dusseldorf.
The twice-weekly flight is to begin in May 2016 and operate on Wednesdays and Sundays.
This is the second major new route announcement for the airport since the beginning of the month.
From October, CityJet will be operating an 18-flights-a-week service to London City Airport.
Dusseldorf will be Aer Lingus' second German destination from Cork Airport. The airline also serves Munich on a year-round basis.
Germany is the world's largest outbound tourism market. Last year, more than 560,000 Germans visited Ireland and growing visitor numbers from Germany is a key target for the Irish tourist industry.