The aircraft will be initially used on the Dallas/Fort Worth-Sao Paulo route starting on Jan. 31. American said it also plans to use the 777-300 on routes to London Heathrow from DFW and New York's JFK airport.
"This is an important step in demonstrating how American is focused on putting our customers at the center of everything we do," said chief commercial officer Virasb Vahidi.
The carrier added the aircraft was delivered without American's traditional livery. On Monday, American posted a video on its Youtube account that featured an aircraft with the tail hidden by black tarps. It appears likely the airline will unveil its new brand, livery and logo with the launch of its new 777-300.
American had originally expected to launch the new 777-300 in mid-December but delayed its entrance into the fleet because of manufacturing issues with the first class seats it has installed in the aircraft.
UPDATE: If you want to follow the plane on its journey from Seattle to DFW, click here.