Dubai’s tally reached 78m million, an increase of 7.5m, according to figures released yesterday.
While Atlanta Hartfield- Jackson, the main base for Delta Air Lines, remains the busiest airport, its total of 101.5m customers rose only 5.3m.
Beijing Capital airport added 3.8m to reach 89.9m customers.
The Gulf hub passed former world No 3 London Heathrow by total passengers, with the UK airport able to increase its numbers by only 1.6m to 75m, hampered by a lack of operating slots on its two crowded runways.
Dubai had already overtaken Heathrow as the busiest airport by international traffic in 2014.
Last year, it also overhauled the former global No 5, Los Angeles, even as the US hub added 4.3m passengers to reach 74.94m.
Tokyo Haneda, ranked the fourth-busiest airport in 2014 with 73m passengers, has yet to publish 2015 figures and could yet displace Dubai as world No 3.
It seems unlikely to do so after ranking behind the Gulf hub in the first six months with less than half the growth rate, according to Airports Council International data.
Emirates boosted passenger numbers 9% last year to 51.3m after swelling the world’s largest fleets of Airbus A380s and Boeing 777s with the purchase of 26 new aircraft.
That is equal to two-thirds of total traffic at Dubai International. The airport also attracted flights by 12 new carriers, with India remaining the most popular market, followed by the UK and Saudi Arabia.
Dubai International plans to take capacity to 90m passengers a year, allowing for further growth before the main expansion of the sheikdom’s new Al Maktoum airport.
That project could one day handle 240m passengers.
It emerged last week that Emirates will overtake Qantas later this month in offering the world’s longest direct flight, to Panama City from Dubai, using a Boeing 777-200LR aircraft.
The Australian carrier’s Sydney-Dallas route is currently the world’s longest.