Turkish Airlines has finalised an agreement to acquire 10 Boeing 737-900ERs and 10 737-800s.
The flag-carrier disclosed a tentative deal to take the twin-jets last month.
Boeing has confirmed that the two sides have concluded the agreement, adding that the order had previously featured on its backlog books, attributed to an unidentified customer.
The airframer, which values the order at $1.6 billion at catalogue prices, says the aircraft will be fitted with its 'Sky Interior' cabin.
Turkish Airlines had previously stated that the aircraft would be delivered from 2011-14, and that the deal included options on another 15.