Kazakhstan's Air Astana is the first to secure a lease of the long-range version of the Airbus A321neo.
The aircraft will come from the jet's first customer, Air Lease.
Air Astana will take a batch of five A321neo and two A320neo jets from the US lessor.
Four out of the five larger aircraft will be the long-range variant, which will have a maximum take-off weight of 97t.
Air Astana chief executive Peter Foster says they will be used to replace Boeing 757-200s in its fleet.
Two A320neos, the first to be delivered in spring next year, will complement the agreement. The remaining jets, including the A321neos, will arrive in 2018-19.
Air Lease has a long connection with Air Astana, having been the source of some of the carrier's aircraft during its start-up phase.