Dubai International has taken over from Heathrow as the world's busiest international airport in terms of yearly passenger numbers.
The United Arab Emirates airport said it had just under 70.5 million passengers through in 2014, compared with around 68.1 million for Heathrow.
Dubai Airports said it had reached a "historic milestone".
Heathrow has been trying to increase capacity for a number of years, a spokeswoman said.
The airport operates at around 98% capacity,
"Britain has benefited from being home to the world's largest port or airport for the last 350 years. But lack of capacity at Heathrow means we have inevitably lost our crown to Dubai," the Heathrow spokeswoman said.
Dubai passenger numbers rose 6.1% in the year, Dubai Airports said.
"The shared goal is to make Dubai a global centre of aviation," said Sheikh Ahmed Bin Saeed Al Maktoum, chairman of Dubai Airports.