The victory left the Americans, who are seeking their first world title in 64 years, with a perfect record of three wins and lifted them to joint first place with Sweden in Pool B.
Marty McInnis collected the winner midway through the final period when he snapped a point-blank wrist-shot past the Italian netminder, Mike Rosati. Paul Ranheim later added an insurance goal into an empty net to close the scoring.
Dan Plante had put the Americans 2-1 ahead just 18 seconds into the final period when his cross-ice pass deflected in off the skate of Robert Nardella. Dino Felicetti then replied for Italy to make it 2-2.
Italy had taken a 1-0 lead in the first period, Chris Bartolone blasting a slapshot past Chris Terreri. The US levelled the score in the second period when Rosati was unable to control the rebound off Ken Klee's shot from the point, leaving a loose puck for Chris Tancill to tap in.