Needing a perfect 10 with his last shot, Michele Frangilli, shooting with Marco Galiazzo and Mauro Nespoli, hit the centre of the target to give Italy a 219-218 win at Lord's Cricket Ground.
"I watched the flight of the arrow and I knew I needed it because it was the last one. I was under so much pressure because time was running out," said Frangilli.
It was a heartbreaking loss for the Americans, who had defeated defending champions South Korea in the semi-final.
The Koreans had to settle for the bronze medal after beating Mexico in the play-off.