The former Chelsea manager had been in charge of the Red Devils since May 2016.
He leaves the club with United sitting sixth in the English Premier League following Sunday’s 3-1 defeat at rivals Liverpool.
The Old Trafford club confirmed Mourinho’s departure in a brief statement this morning.
It read: “Manchester United announces that manager Jose Mourinho has left the club with immediate effect.
“The club would like to thank Jose for his work during his time at Manchester United and to wish him success in the future.
“A new caretaker manager will be appointed until the end of the current season, while the club conducts a thorough recruitment process for a new, full-time manager.”
Michael Carrick has been appointed interim manager until the end of the season.
Manchester United searching for new manager after sacking Jose Mourinho