The Red Devils were humbled by Liverpool on Sunday as they were beaten 3-1 by their fiercest rivals at Anfield.
And United have decided that result was the final straw and have partied company with the Portuguese.
A club statement 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.”
Mourinho spent two-and-a-half years in the Old Trafford dugout and won the EFL Cup and the Europa League in the 2016-17 season.
But the defeat at Liverpool left the Red Devils 19 points off their fiercest rivals who currently top the Premier League.
Finishing in the top four is a minimum requirement for United this term and they are already 11 points adrift.
Mourinho was a vocal critic of United’s transfer policy after he failed to land any of his prime defensive targets last summer.
He was desperate to sign a big-name centre-half with Toby Alderweireld and Harry Maguire among the names on his shortlist.
And United have now grown tired – pulling the trigger on Mourinho and announcing they will appoint a caretaker boss until the end of the season.
Sky Sports reports that an external appointment is expected within 48 hours from Manchester United.
Meanwhile, Carrick and Kieran McKenna will continue to take training in the meantime.
It is reported that Zinedine Zidane is the hottest favourites to replace Jose Mourinho.