"Perry Fewell will be our interim head coach," Bills owner Ralph Wilson said in a statement. "Perry has done a great job with our defense and has demonstrated excellent leadership skills as defensive coordinator."
Fewell, 47, became a head coach for the first time after working 12 years as an NFL assistant coach. He was Jauron's defensive coordinator for the past four seasons, the team said.
The announcement came only hours after Wilson announced Jauron had been fired midway through his fourth losing season.
The Bills are 3-6 this season after a 41-17 thumping by Tennessee Sunday and have finished 7-9 in each of Jauron's three complete seasons leading the team.
Before joining Buffalo, Jauron, 59, spent two seasons with Detroit as defensive coordinator and produced a 1-4 mark as interim coach of the Lions in 2005.
Jauron also had a losing record as coach of the Chicago Bears, going 35-46 in five seasons from 1999 through 2003.
He was the NFL Coach of the Year in 2001 when the Bears went 13-3, his only winning season.