Chief executive Stewart Wingate said much of the growth has been driven by the long-haul market following a growth of 26% in routes in the sector.
He added Canada has performed particularly strongly with Winnipeg up by 66.3% in June, followed by Edmonton at 28.2%, Montreal at 23.8% and Calgary at 13%.
Other long-haul routes that experienced significant year-on-year growth in June included Lima with 29.6% and Kigali on 19.9%.
Meanwhile emerging short-haul destinations Volos and Tallin saw passenger growth rates of 154.7% and 51.4% respectively.
The strong growth across many of its routes meant 4.5 million travellers passed through Gatwick in June.
And Wingate added the busiest days in the next two months include July 20, when 86,000 passengers are expected to jet away while September 2 will see 88,400 travellers pass through the airport upon their return.
August 12 will be the overall busiest day for the airport with a total of 167,200 travellers departing and arriving at Gatwick.
Orlando remains the most popular summer long-haul destination, with Doha a new addition to the top 10 list after a double-daily service to the city was launched by Qatar Airways in May.
In terms of the most popular short-haul routes, Nice joins the top ten list this year, while Barcelona remains Gatwick’s top summer short-haul destination.
Wingate said: “Just one week after we added a 67th long-haul service to our extensive network – with the launch of the UK’s only direct flights to Chengdu with Air China - it’s fantastic to see that our long-haul routes are continuing to perform so strongly, with solid growth recorded in June."