A trial of allocated seating will be conducted by easyJet at a cost of up to £12 per passenger.
Travellers will be given the option of paying for extra legroom or seats at the front of the cabin.
The trial from April will be carried out on routes from Luton to six destinations including Malaga, Istanbul and Glasgow.
Passengers will be able to pay £3 to select their seats. But exit row and front row seats – with extra legroom – will cost an additional £9, and those towards the front an extra £5.
EasyJet hopes the move will appeal to business travellers who tend to book later, buy flexible fares and are less concerned about price.