A 2-1 home loss to Chelsea, who are managed by their former coach Enzo Maresca, left Leicester 16th in the standings with 10 points after 12 games.
"Leicester City has parted company with Steve Cooper, who leaves his position as first team manager with immediate effect," the club said on Sunday.
"Assistant manager Alan Tate and first team coach and analyst Steve Rands have also left the club."
Leicester said first team coach Ben Dawson, and coaches Danny Alcock and Andy Hughes will oversee training until they find a new manager.
Cooper, sacked by Nottingham Forest last season, was appointed in June to replace Maresca who had led the club to promotion.
Leicester failed to record a win in their opening six league games, however.
Successive victories over Bournemouth and Southampton last month eased the pressure before three defeats in their last four games led to Cooper's downfall.
Cooper, 44, is the second EPL manager to be sacked this season after Manchester United parted ways with Erik ten Hag last month.
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