كتب : Omar AbdelAziz
The decision comes after a series of poor results which saw the team extend their winless streak to nine games this week.
Allegri helped relegation candidates Cagliari finish ninth in the Italian league last season; an achievement that saw him named 'Coach of the Year' by fellow professionals in 2009.
Cagliari, who will now be managed by youth coach Giorgio Melis, are currently 12th in the Serie A table.