They are set to strike for nine days at the height of the summer holiday season in July.
The budget airline's attendants will walk out in three phases across the month - between July 1 and 3, between 15 and 17, and finally between 29 and 31.
The planned walk-outs will add to the disruption during a holiday season which is already looking set for more chaos.
Responding to easyJet’s announcement on summer flight cancellations, Rory Boland, editor of consumer magazine Which? Travel, said: “EasyJet has caused chaos and distress for passengers over several weeks with a constant stream of last-minute cancellations.
“While reducing the number of flights it operates may be the most sensible option in delivering a more reliable service over the summer, it yet again leaves passengers panicking about whether their flight or holiday will be cancelled or delayed.
“The summer holidays are just around the corner, so easyJet must immediately provide clarity on which flights are being cut.
“Crucially, it needs to start playing by the rules and rerouting its customers, including on flights with other carriers.
“That’s the legal requirement and the very least the airline can do for customers it has left in a mess.”