City Ground chiefs have taken the decision in the wake of yesterday’s 1-0 defeat to Sunderland.
Forest, who avoided relegation on goal difference last season, have won 10 but lost 14 of their 25 games this term.
Warburton leaves with the club sitting 14th in the Championship table.
Warburton’s assistant David Weir and director of football Frank McParland have also been axed.
Forest academy boss Gary Brazil has taken caretaker charge.
A statement from the club read: “The club would like to thank Mark, David and Frank for all their efforts during their time at The City Ground.”
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