The club have reacted swiftly to the 3-0 loss in Italy last night which took their hopes of reaching the last 16 out of their hands, and put them at risk of becoming the first holders to fail to reach the subsequent knockout phase.
The Blues have also failed to win any of their last four Premier League games, a run which has seen them slip from top to four points behind leaders Manchester City.
A club statement read: "Chelsea Football Club has parted company this morning with manager Roberto Di Matteo.
"The team's recent performances and results have not been good enough and the owner and the board felt that a change was necessary now to keep the club moving in the right direction as we head into a vitally important part of the season.
"The club faces a difficult task ahead in qualifying for the knockout stages of the UEFA Champions League as well as maintaining a strong challenge for the top of the Premier League while competing in three other cup competitions. Our aim is to remain as competitive as possible and challenge strongly on all fronts.
"The owner and the Board would like to thank Roberto for all he has done for the club since taking over in March. Roberto helped guide us to an historic Champions League victory and a seventh FA Cup. We will never forget the huge contribution he has made to this club's history and he will always be welcome at Stamford Bridge.
"The club will be making an announcement shortly regarding a new first team manager."