The Luton-based carrier said it intends to reduce its workforce by up to 30% as it cuts the size of its fleet due to the coronavirus pandemic.
This follows similar moves by other airlines such as British Airways and Ryanair.
EasyJet has around 15,000 full-time employees, meaning a maximum of 4,500 jobs are at risk.
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The low-cost airline's chief executive, Johan Lundgren, said: "We realise that these are very difficult times and we are having to consider very difficult decisions which will impact our people, but we want to protect as many jobs as we can for the long term.
"We remain focused on doing what is right for the company and its long-term health and success, following the swift action we have taken over the last three months to meet the challenges of the virus."Although we will restart flying on 15 June, we expect demand to build slowly, only returning to 2019 levels in about three years' time.
"Against this backdrop, we are planning to reduce the size of our fleet and to optimise the network and our bases."
EasyJet announced that by the end of next year it expects to have reduced its fleet size by around 51 aircraft to approximately 302.
This will be achieved through measures such as deferring new aircraft arrivals.
Bookings for winter are "well ahead of the equivalent point last year", partly due to some customers rebooking flights which were cancelled due to the pandemic.
Brian Strutton, general secretary of pilots' union Balpa, said easyJet staff will be "shocked at the scale of this announcement".
"Given easyJet is a British company, the UK is its strongest market and it has had hundreds of millions in support from the UK taxpayer, I can safely say that we will need a lot of convincing that easyJet needs to make such dramatic cuts," he said.
"Indeed, easyJet's own projections, though on the pessimistic side, point to recovery by 2023 so this is a temporary problem