Boeing Chief Executive Kevin McAllister added: "This new order is a powerful endorsement of the 787 family's unique passenger appeal and unmatched ability to help airlines open new routes and grow profitably".
The company also sung the Boeing 787 Dreamliner's praises. ANA, the Japanese carrier that was the launch customer for the Dreamliner, is the largest operator of 787s, while lessor AerCap is the largest 787 owner.
Boeing beat its rivals to the order and will supply 47 of the long-haul, two-aisle aircraft, in a deal worth more than £8 billion.More news: Dwayne "The Rock" Johnson Talks Depression, Urges Others to "Open Up"
American has been looking at alternatives for the order for 22 A350s that it gained through its 2013 merger with US Airways since previous year, and recently outlined a need to make a decision on what to do with its aging 767-300ER fleet.
The sudden shift is a blow to France-based Airbus, who have supplied American Airlines with almost three dozen 787s. With the purchase of additional 787s, American will have just three different wide-body aircraft types in its fleet - the 787, Boeing's 777 and Airbus' A330-200.
Under American's fleet plan before Friday, the airline expected to fly five types of widebody jets going forward.More news: Hearing resumes in Jodhpur court on Salman's bail plea
Choosing between Boeing and Airbus was a "difficult decision", the airline's president, Robert Isom, said in a news release, but going with Boeing to simplify the fleet "made the 787 a more compelling choice". It already plans to shed another small fleet of 20 Embraer E190 jets. The 787-8s will be delivered from 2020 and the 787-9s from 2023.
The airline also reached an agreement with Boeing to defer the delivery of 40 737 MAX aircraft due to arrive between 2020 and 2022.
Airbus has said it has a series of ongoing sales campaigns for the A330neo with more than 100 airlines that now operate the older version of the plane.More news: Salman should be given relief for his humanitarian work: MP Jaya Bachchan