The launch of Norwegian Air Shuttle transatlantic services helped Gatwick achieve record monthly passengers of more than 4.057 million in July.
The total was up by 6% or 229,500 on the same month last year, with the Norwegian Boeing 787 Dreamliner services to New York, Los Angeles and Fort Lauderdale contributing to a 6.6% rise in North Atlantic traffic.
Other long haul routes saw growth of 8.9%, with Dubai seeing an increase of 6.7%.
The previous highest monthly total – 4.032 million – was seen in August 2013.
European scheduled traffic showed growth of 10.5% or 226,000 passengers in July. Business routes including Paris, Brussels and Amsterdam boosted traffic alongside growth to cities including Stockholm and Rome.
Increased frequencies to Turkey earlier this summer translating into a 21.8% year-on-year rise in traffic to Istanbul.
The airport’s chief financial officer Nick Dunn said: “The strength of Norwegian’s new low-cost long haul flights on new-generation aircraft is really encouraging.
“What passengers want is the convenience of flying from their local airport to the destination of their choice with fares they can afford.”
And he claimed: “Building a third runway at Heathrow will diminish the choice available to British passengers, making it more expensive to go on holiday, to travel for business and to export goods and services.
“We support competition, reduced fares and two world-class London airports serving the UK as a whole.”