The Portuguese manager has been shown the door after blasting the club's management following their 1-1 draw at Leeds United on Sunday.
United announced this morning: "Ruben Amorim has departed his role as head coach of Manchester United.
"Ruben was appointed in November, 2024 and led the team to a UEFA Europa League Final in Bilbao in May.
"With Manchester United sitting sixth in the Premier League, the club’s leadership has reluctantly made the decision that it is the right time to make a change. This will give the team the best opportunity of the highest possible Premier League finish.
"The club would like to thank Ruben for his contribution to the club and wishes him well for the future.
"Darren Fletcher will take charge of the team against Burnley on Wednesday."
The decision ends Amorim's reign after 18 months at Old Trafford, where his back three playing system was brought into question both inside and outside of the club.
The rant that ended it all
After Sunday's draw at Elland Road, Amorim let loose on the club's top brass, hinting at broken promises.
He said on Sunday: "I came here to be the manager of Manchester United, not to be the coach of Manchester United. And that is clear. I know that my name is not Tuchel, it's not Conte, it's not Mourinho, but I'm the manager of Manchester United.
"And it's going to be like this for 18 months, or when the board decides to change. So that was my point, I want to finish with that. I'm not going to quit. I will do my job until the other guy is coming here to replace me."
Amorim also suggested promises had been broken regarding having the power to shape the culture inside the club.
"I just want to say that I'm going to be the manager of this team, not just the coach," he said. "And I was really clear on that. And that is going to finish in 18 months and then everyone is going to move on. That was the deal.
"That is my job, not to be a coach. If people cannot handle the Gary Neville and the criticism of everything, we need to change the club. No, guys, I just want to say that I came here to be the manager of Manchester United, not to be the coach.
"And every department, the scouting department, the sports director needs to do their job. I will do mine for 18 months and then we move on."
Former United midfielder and captain Darren Fletcher steps up from his U18 role to take charge on a caretaker basis.