It is buying 35 Airbus A320 neo aircraft with the option for up to 71 jets.
The potential value is $8 billion at list prices.
The firm ordered aircraft deliveries stretch over three years until 2031.
This order, which is in addition to the A321 neo aircraft orders announced in 2021, means Jet2 now has a total of 98 jets on order.
Financing will be through a combination of internal resources and debt.