Heathrow reported an early start to the summer getaway by handling more than seven million passengers in June.
The increase of 17.5% over the same month last year came as transatlantic travel continued to drive passenger numbers, with almost two million flying to and from North America.
The figures came after the London hub reached an agreement on pay deal to prevent strikes by security guards over the summer.
A spokesperson said: “We are pleased to have agreed a two-year pay deal which helps colleagues with the cost of living crisis and means that travellers can be confident that their travel plans won’t be affected by strike action.”
Heathrow described service levels last month as being “very high”, with security queues under five minutes across all terminals and ‘Here to Help’ teams out in force.
The spokesperson added: “More families arriving back at Heathrow from their summer holidays are set for a speedier immigration experience after Border Force announced that all children over 10 will be able to use eGates instead of queueing to see an immigration officer.”
The airport is seeking to counter cost pressures by introducing free meals for children aged under 12 at family-friendly restaurants from July 20 until September 3.
Children aged under 15 can also travel free of charge on the Heathrow Express.
Outgoing chief executive John Holland Kaye said: “I am very proud of the way that everyone at Heathrow has been working together to deliver excellent service at our busiest time of year.
Summer at Heathrow is all about family holidays and we are ready to make sure yours gets off to a great start.“