Ethiopian Airlines now operates a fleet of six Boeing 777 freighters and two Boeing 757 freighters, operating to 39 cargo destinations in Africa, the Middle East, Asia and Europe.
The deal includes a new order for two aircraft, along with two others the airline announced as a commitment in June and which have now been converted into firm orders.
This order pushes 777 net orders this year to 57 - 37 of them for the current-generation 777 airplane - providing further support to a smooth production transition to the new 777X. The airline opened a state of the art cargo terminal back in June, boosting the carrier's annual capacity to one million tons.
Gulf-based airline Emirates had been expected to announce it was ordering more than 30 of the aircraft in a $10bn (£7.6bn) deal on the first day of the Dubai airshow on Sunday.
The deal, including airplanes and related equipment, is valued at Dollars 15.1 billion at current list prices.
Azerbaijan Airlines also announced it would be the launch customer for the 787 Landing Gear Exchange Program whereby Boeing Global Services will provide the carrier with a lower-cost solution for overhauled and certified landing gears for its Dreamliner fleet, which now numbers seven aircraft.