Each bag - weighing up to 20kg - will cost £2. Currently the first bag is free but each subsequent bag costs £5.
"It's about getting people to pack smarter, travel lighter and travel cheaper," Easyjet said.
Its policy on carry-on luggage will not be affected.
Rival Ryanair already charges for all bags that are checked in.
The airlines say that handling fewer bags can help airports run more smoothly - and argue that those who do not have luggage should not have to pay for those who do require the service.
In February British Airways announced that some travellers would pay to check in a second piece of luggage.