Army Colonel Steve Warren said the Pentagon was "reasonably certain" the drone strike carried out overnight on Thursday in Raqqa, in northern Syria, killed the infamous militant.
"This guy was a human animal, and killing him is probably making the world a little bit better place," Warren told reporters.
"Jihadi John," a British national whose real name was Mohammed Emwazi, became the face of terror after he appeared in a video circulated online by the "Islamic State" (IS) militant group that showed him beheading a US journalist.
A figure of terror
Earlier on Thursday, US and British authorities rushed to declare the strike a success, while declining to confirm whether or not the infamous jihadist was in fact dead.
British Prime Minister David Cameron said the strike was the "right thing to do," calling it "an act of self-defense." US Secretary of State John Kerry, meanwhile, said the strike showed that the "terror group's days were numbered."
Emwazi was born in Kuwait but emigrated to England when he was a boy. After what appears to have been a normal middle-class upbringing, the young man became radicalized after traveling to Tanzania.
He was one of three British-sounding IS militants dubbed "the Beatles" by the media and former captives.
Arrest in Turkey
The AFP news agency meanwhile reported that one of Emwazi's associates was arrested in Turkey.
Aine Lesley Davis, also a British citizen, was arrested during a raid in Istanbul. Turkish officials said that Davis has long been regarded one of Emwazi closest collaborators, adding that they were "99 percent certain" that the person in custody was indeed Davis.
It was not clear wether Davis is one of those dubbed to be part of "the Beatles" group.
blc, ss/kms (dpa, Reuters, AP)