Lessor Air Lease has underpinned the Airbus A350-1000 by ordering five of the type as well as 20 A350-900s.
The leasing firm has also firmed options on 14 A321neo twinjets.
Airbus says the company has options for five more A350-1000s. The deal marks the third endorsement of the largest member of the A350 family since its redesign.
The order takes the A350 backlog to more than 600 aircraft.
Air Lease's A321neo deal follows its earlier pact for 36 A320neo jets at the 2012 Farnborough air show.