Mourinho was filmed by Sky Sports leaving the Lowry Hotel just hours after being told the news of his dismissal.
The Portuguese could be heard saying “bye guys” to people waiting for him to appear outside the hotel where he has been staying ever since he took over the club in 2016.
Mourinho leaves the club after two and a half years in charge with United struggling badly.
United have put Michael Carrick in temporary charge but they will appoint somebody to guide them through the rest of the season within the next 48 hours.
United are currently sixth in the Premier League table – 19 points off the top and 11 points off the pace in the race for the top four.
He started well at Old Trafford, guiding the club to Europa League and League Cup glory in his first season in charge.
However, things quickly turned sour this term and he had been at odds with the United board ever since they failed to back him by signing a new centre-back in the summer.
His relationship with record signing Paul Pogba was also strained, with the pair involved in a number of public fall-outs throughout 2018/19.
The Frenchman was stripped of the vice-captaincy when he questioned Mourinho’s tactics after a disappointing 1-1 draw with Wolves in September.
Pogba also posted a video of himself laughing after they lost to Derby in the League Cup, although it was later claimed he tried to post it during the game but the upload failed because of a poor WiFi connection at Old Trafford.
Mourinho is also reported to have called him a virus in a stunning dressing room bust-up at St Mary’s following the recent 2-2 draw with Southampton.
Despite all that, the club were quick to thank him for his service in a statement issued immediately after his sacking.
“Manchester United announces that manager Jose Mourinho has left the club with immediate effect,” the 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.”