The Browns finished the campaign with a 41-9 drubbing by the Pittsburgh Steelers.
"Although we have made improvements this season, my responsibility is to ensure that we establish a program that will allow this team to compete at a championship level," Browns president Mike Holmgren said in a statement.
"That will continue to be our goal in everything we do."
The Browns registered upset victories this season over the playoff-bound New Orleans Saints and New England Patriots but failed to follow up in finishing 2-6 with losses in their last four games.
Mangini, who previously coached the New York Jets, thanked the Browns owners for the opportunity to coach in Cleveland.
(Reporting by Larry Fine; editing by Ed Osmond)
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