BOC Aviation has ordered 50 Airbus A320-family aircraft, including 25 of the re-engined Neo variant.
The aircraft, which comprise both A320 and A321 variants, will be delivered from the second half of 2014 to the end of 2019.
The leasing company has not made an engine selection.
"Airbus's popular A320 and A321 aircraft with the current engine option are outstanding aircraft for airlines focusing on operational efficiency who want to offer their passengers a superior short to medium-haul travel experience," says Robert Martin, BOC Aviation's managing director and chief executive.
"The A320neo-family order reinforces our commitment to be a key player in the leasing industry as we make the latest eco-efficient aircraft available to our customers."
The lessor says that it has a portfolio of 203 owned and managed aircraft operated by airlines worldwide, and another 100 aircraft on firm order.