Demand for long-haul destinations enabled Gatwick to achieve its 51st consecutive month of growth in May.
Passenger numbers rose by 6.7% to more than four million over the same month last year.
The highest number of business passengers also passed through Gatwick last month to hit a record of 782,000.
The airport’s network of more than 50 long-haul routes is driving this growth with North American destinations up by 13% – with 15 cities on the US and Canada now served from Gatwick.
Top destinations last month included Los Angeles (up 48%), Fort Lauderdale (up 125%) and Calgary (up 43%).
Gatwick’s long-haul network is set to grow further when the world’s longest low-cost long-haul route – Norwegian’s service to Singapore – starts in September.
The airline also setting up new services to Seattle and Denver in the same month.
Load factors at Gatwick hit 85% in May, up from 83.1% at the same time last year.
Airport chief executive, Stewart Wingate, said: “There is real momentum behind Gatwick’s growth as records tumble month after month.
“Our continued growth shows that we are an airport that delivers for everyone whether travelling for business or leisure and flying short or long haul, Gatwick has a choice of airlines and destinations unrivalled in the UK.
“The airport’s long haul network has grown significantly and the results benefit both leisure passengers and also the country as global trade becomes increasingly important for the UK economy.
“With this in mind, Gatwick stands ready to build a credible and deliverable new runway should the government give us the green light to proceed.”