The sacking came on the back of a 1-3 loss to Liverpool which meant that Manchester United are daylight behind their rivals and Premier League leaders.
With United 19 points leaders Liverpool and suffering from their worst start since 1990-1991, the club have finally let go of Mourinho.
According to Manchester United’s statement on Mourinho’s sacking, a caretaker manager will be given the ruins until the end of the season 'while the club conducts a thorough recruitment process for a new full-time manager'.
Giving Mourinho the sack mid-way into the season means Manchester United have already given up on the current season and are thinking long-term.
It is this long-term that is more crucial for Manchester United and who should they give the job to?
Pulse Sports look at five candidates for the job.
Dream: Mauricio Pochettino
Mauricio Pochettino had lunch with Manchester United great Alex Ferguson in May 2016 but just a few weeks later, Mourinho was appointed to replace Louis van Gaal who had been sacked. Looking back now, a host of Manchester United fans would have wanted the Tottenham manager at their club.
Since joining Tottenham in May 2014, Pochettino has turned Tottenham ‘s fortunes around. Although still without a trophy, he has managed the club to punch above their weight in the Premier League.
He is the dream candidate to replace Mourinho. Tested and proven in the Premier League and has a good record with developing players too.
The problem is, he’s still under contract at Tottenham and the club ‘s boss Daniel Levy has a reputation of not easily letting go of anyone under his watch.
Realistic: Zinedine Zidane
Zinedine Zidane started his coaching career as a rookie at Real Madrid and left the club as one of the most sought-after managers in European football.
Although there are still doubt over his technical know-how, what he achieved at Real Madrid has made his stock to rise.
He remains the most highly rated coach available and won’t require much to get him on board.
Wildcard: Massimiliano Allegri
Manchester United are one of the biggest sports teams in the world and as such would be overwhelming for a lot of coaches.
A manager who is tested and tried at the biggest club and coach could be the perfect manager to quickly get Manchester United back to the top and no one in top flight football fits the bill like Allegri who has seen and done it all at AC Milan and Juventus.
An astute tactician, Allegri does not resort to defensive scheme to win games, so no conservative football.
He also a shrewd buyer, a manager who has a track record of not overspending on players having assembled one of the most talented squad in Europe without paying over the top for any player.
It might be hard to take the Italian manager away from Juventus, but he could be down with a fresh challenge.
Pulse Sports suggest: Leonardo Jardim
A year ago, Jardim would have been one of the names linked to the job but football is so flaky especially the way managers are rated and that is why the Portuguese is not in the mix.
But he should be after the good work he did as coach of Monaco before his sack.
With Paris Saint-Germain financially edge, no one expected Monaco to pose much of a threat in Ligue 1. Jardim, however, oversaw one of the most sensational Ligue 1 title wins in recent times.
Monaco romped their way to the title scoring 107 goals and finishing the league with 95 points. In Europe, his Monaco side also impressed in the Champions League.
All these without spending much money. In fact, Jardim had to look inwards the Monaco youth team from which he discovered the likes of Kylian Mbappe.
What Manchester United would love about him is the exciting brand of football they played on their way to the title. Quick, incisive and often times devastating.
Critics might point to how Monaco collapsed under his watch the seasons after the league win. But he lost Mbappe and wasn't backed in the transfer window, a problem he wouldn’t have at Manchester United.