Mourinho guided his side to the Premier League title in May but has suffered a freefall this season.
A 2-1 defeat to Leicester on Monday was their ninth of the campaign, leaving them in 16th place.
Mourinho leaves with Chelsea now just a point above the relegation places.
A Chelsea statement read: "Chelsea Football Club and Jose Mourinho have today parted company by mutual consent.
"All at Chelsea thank Jose for his immense contribution since he returned as manager in the summer of 2013.
