That knocked around 5 million pounds off its revenue and cost the airline 10 million pounds to help its customers.
However the group gave an otherwise upbeat trading update and said 2019 bookings were encouraging despite uncertainty around Brexit, striking a more positive tone than rival Ryanair <RYA.I>, which issued a profit warning last week.
"We feel that this environment is robust and solid, and we do well in it," Chief Executive Johan Lundgren told reporters.
Gatwick was forced to close its runway in December when drones flew near the site south of London in the most disruptive incursion by unmanned aerial vehicles at any major airport.
It forced the cancellation or diversion of around 1,000 flights, affecting 140,000 passengers over three days in total.
Analysts at RBC said they had trimmed their profit-before-tax forecast for easyJet by 3 percent as a result of the Gatwick disruption, but retained their "outperform" rating as "far worse" earnings cuts were already priced-in.