An air-traffic control "gold emergency" was declared after an issue in the control tower.
As of 7:10pm local time flights have resumed, the airport said on Twitter. The exact problem has not been revealed.
Gatwick Airport suspended flights for over an hour on Wednesday evening due to a "systems issue".
But after around three hours of disruption, the airport released a statement that flights are back to normal. The airport did not say what the problem might have been.
Passengers due to travel to or from the airport have been advised to check for updates with their airline.
The Guardian reported that the cancellations and delays affected flights in other European cities, including Gothenburg, Sweden; Bilbao, Spain; and Bergen, Norway.