Manchester and Stansted airports each handled more than 2.5 million passengers last month.
The sister MAG-owned airports were helped by multiple bank holidays and the half-term school break in May.
Manchester airport was also boosted as it handled more than 100,000 passengers on a single day on June 9 for the first time since pre-pandemic 2019 as Manchester City fans flew to Istanbul for the Champions League final.
Stansted’s passenger numbers in May grew by 19% year-on-year to more than 2.55 million, while Manchester saw a 15.5% rise to surpass 2.5 million.
The Essex airport recorded its busiest day of the year so far with 92,920 passengers passing through the terminal on May 29.
The busiest day of flights was on May 26 with 602 arrivals and departures.
Both airports reported that 96% of passengers passed through security in 15 minutes or less.
The busiest route from both airports was to Palma in May.
Stansted chief operating officer Jon Fowler said: “This May was a really busy and positive month for London Stansted with the three bank holidays and half-term school break boosting passenger numbers.
“We welcomed many people flying into the UK from around Europe for the King’s coronation, while many Brits took advantage of the additional day off to head away on holiday or visit family and friends.
“We know our passengers want a reliable and efficient experience when passing through the airport, and as we look ahead to even busier days across the peak of summer, we will continue our work with our business partners across the campus to ensure that’s what we all deliver.”
Manchester airport managing director Chris Woodroofe said: “Football is such an important part of life for many people so it was a real privilege for all of us at Manchester Airport to be able to help thousands of fans get out to Istanbul smoothly and share in an unforgettable experience.
“As the UK’s global gateway in the north we play a key role in making sure that people in the region can get to major global events like the Champions League final. It shows that we’re ready for a successful summer and that people can feel confident they’ll get a great experience at the airport as they start their holidays.
“Passenger numbers increasing year-on-year shows the importance of international travel to people in the area so whether you’re heading to Palma for a family holiday or jetting off to Dubai on business you’ll get the best start to your journey here at the airport.”
Meanwhile, MAG’s third airport, East Midlands, handled around 400,000 passengers in May – up 12% on 2022.
MAG’s rolling 12-month passenger total to May 2023 stood at 55.5 million passengers – up 92% on the total to May last year.