Kent Brantly was given ZMapp, a drug used on a handful of patients in the West African outbreak and produced by US-based Mapp Biopharmaceutical.
Georgia's Emory University Hospital in Atlanta treated Dr Brantly and a second American, Nancy Writebol who has also been discharged.
Franklin Graham, president of the Samaritan's Purse charity Dr Brantly works for, said: "I have marvelled at Dr Brantly's courageous spirit as he has fought this horrible virus."
Mapp says supplies of the drug have been exhausted.
Almost 2,500 people have been infected and 1,350 have died since the Ebola outbreak was identified in Guinea in March.