The Red Devils currently sit sixth in the Premier League table but have already lost five times in 17 matches, leaving them 19 points behind leaders Liverpool and 11 off fourth-placed Chelsea in the fight for Champions League places.
That follows a summer transfer window in which Mourinho routinely complained at a lack of signings, with the Portuguese unable to persuade the club’s hierarchy to sign a new centre-back.
“Manchester United announces that manager Jose Mourinho has left the club with immediate effect,” a statement read.
“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 replaced Louis van Gaal in the United hotseat in the summer of 2016 and was tasked with leading the 20-time English champions back to the top of the domestic game after a barren three years since Sir Alex Ferguson’s appointment.