Paris Charles de Gaulle has overtaken Heathrow as the largest airport in Europe for the first time, with Amsterdam Schiphol and Frankfurt close behind.
The shakeup comes in the wake of the Covid-19 pandemic that has seen travel slump across the continent.
All three European airports have implemented testing regimes, with Heathrow repeatedly calling for government action to boost travel in the UK.
The UK government has announced an intention to introduce testing for passengers from high-risk countries from December to help restart the UK economy, but further details are expected.
Heathrow has also revised down expected passenger demand figures for next year.
Passenger numbers are now forecast to be 22 million this year, and 37 million in 2021, compared to a June forecast of 29 million this year and 63 million in 2021.
Heathrow welcomed 81 million passengers last year.
Heathrow chief executive, John Holland-Kaye, said: “Britain is falling behind because we have been too slow to embrace passenger testing.
“European leaders acted quicker and now their economies are reaping the benefits.
“Paris has overtaken Heathrow as Europe’s largest airport for the first time ever, and Frankfurt and Amsterdam are quickly gaining ground.”