The club confirmed this morning that after 27 years at the helm, the 71-year-old will step down from his position at the end of the current campaign.
So, who is going to follow a man that has won 49 trophies during his time at Old Trafford? The rumour mill is already in full swing, but who are the early contenders? Sports Mole reveals all below.
For a number of years now, the name of Moyes has always, albeit sometimes in the shadows, been linked with replacing his fellow Scot. However, over the past 48 hours, he has been made the favourite with the bookmakers to take over at Old Trafford. Some reports have even claimed that he would be appointed Ferguson's assistant for a season or two. We now know that isn't the case, but he is still a frontrunner. What may count against him is his lack of European pedigree.
Taking over from Ferguson is a job that many believe only someone with an ego like 'The Special One' could handle. The Portuguese coach has proved himself time and again at the top level in England, Spain, Italy and Portugal. He also knows about the pressure of dealing with big-name players, unlike Moyes. However, if rumours are to be believed, he is not a popular choice among some members of the Man United board. Speculation has also claimed that a deal for him to return to Chelsea is done.
While 45-year-old Klopp has only risen to prominence this season in the eyes of the football world, he has been going about his job with Borussia Dortmund since 2008 quietly and astutely. Two Bundesliga titles, a German Cup and an appearance in this year's Champions League final later and Klopp has now found his name linked with the vacancy. It is also believed that he has clause in his contract that allows him to talk to clubs overseas.
It would be the emotional appointment. The Norwegian is a legend among the United supporters, having scored numerous important goals during his 11-year stint as a player with the club. He's also done his coaching badges under Ferguson's guidance and had a spell in charge of the reserves. He has since guided Molde to two league titles in his homeland, but a move to his former club would be a major step up.
The Chilean has recently been linked with another Premier League club - Chelsea. He has many admirers, particularly because of his work at financially-stricken Malaga. What may work against the 59-year-old with this job though is the lack of managing a big European club on his CV. But for a one-year spell with Real Madrid, he has limited experience at managing at the very top level.