Green Africa Airways, a new Nigerian airline, has ordered 50 Airbus A220s, the wings of which are manufactured at a factory in Belfast.
The deal is seen as important because Green Africa initially expressed interest in ordering a fleet of Boeing 737 Max aircraft.
The Max has been immobilized since March 2019 after two separate accidents killed 346 people.
The airline owner said it was the largest order for A220 from Africa.
"With Airbus, we are extremely proud to announce the largest order ever made for the A220 from the African continent," said Green Africa Airways founder Babawande Afolabi.
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Meanwhile, Canadian aerospace company Bombardier sold its remaining stake in the A220 project to Airbus for $ 591 million (£ 455 million).
Airbus first invested in the project in 2017 at a time when Bombardier was experiencing financial difficulties.
Last year, Bombardier agreed to sell the Belfast wing plant to Spirit Aerosystems.
The agreement, which includes Bombardiers' other operations in Belfast, is expected to close later this year.
The A220 began life under the name of Bombardier CSeries.
However, the development of the CSeries took place on time and on budget and threatened to tip Bombardier into insolvency.
The Canadian state of Quebec also invested in the CSeries, which was in fact a bailout.
Quebec retains a 25% stake in the A220.