Trestman guided the Bears to a 5-11 record and a last-place finish in the NFC North this season after failing to secure a winning record in his first season in charge.
The former Canadian Football League coach, who won two Grey Cup titles with the Montreal Alouettes, was unable to inspire an inconsistent offense and a defense that fell apart consistently .
His fate was sealed over the second half of the campaign which included back-to-back blowout losses to the New England Patriots and Green Bay Packers which saw the Bears become only the second team in NFL history to give up 50 points in successive games.
Only the Oakland Raiders (452) gave up more points than the Bears (442) this season.
Trestman was also criticised for his decision to keep offensive coordinator Aaron Kromer after he told the team he was the source of an NFL Network report that criticised quarterback Jay Cutler – Cutler was benched six days later but returned for their final game at Minnesota on Sunday.
Emery was responsible for hiring Trestman before the start of the 2013 season and his reign was marked by a mixed set of results and criticism of his contractual dealings and draft strategy.
Trestman’s dismissal was the fourth of ‘Black Monday’ coming after Jim Harbaugh left the San Francisco 49ers, Rex Ryan was fired by the New York Jets and the Atlanta Falcons released Mike Smith.