The Lions lost 27-7 to the Falcons on Thanksgiving Day, dropping their record to 4-7 and 15-28 under Mariucci, placing them behind the NFC North Division leading Chicago Bears (8-3) and the Minnesota Vikings (6-5), with five games left in the regular season.
"We started off this season with high expectations. I believed this was a roster that was capable of making a playoff run," said Lions' president Matt Millen. "We have not lived up to our expectations."
Jauron compiled a 35-46 record as head coach of the Bears from 1999-2003.
Mariucci, 50, who has an overall NFL record of 75-71, was fired by San Francisco in 2002. He has two years left on a five-year contract. The Lions were 5-11 in 2003 and 6-10 in 2004.
Detroit plays Minnesota this weekend.