A new order for 35 aircraft is expected to be worth almost $4 billion.
The second largest tour operating group in the UK has an option to double the deal to 71 aircraft.
The future anticipated growth of the Jet2 leisure travel business is one of the reasons for the new order.
The company said it had negotiated significant discounts from the base price of the A320neos.
Jet2 now has a total of 98 aircraft on firm order, which could eventually grow to as many as 146.
Just over a year has passed since Jet2 placed its first order for 36 A321neo.
The A320neos will have 180 seats with a cabin with innovative lighting, new seating, and larger overhead baggage bins.
Jet2 will retain flexibility in determining the most favorable way of financing the aircraft, which will be through a combination of internal resources and debt.
Philip Meeson said, "We are delighted to build on our existing relationship with Toulouse and to have placed this additional aircraft order which provides the company with certainty of supply well into the next decade."
The order reflects our confidence that we have a much-loved product built on sector leading customer service which we can continue to grow and these aircraft will ensure our customers have a wonderfully comfortable and enjoyable experience.