He inherited a team that had won the Premier League title by 11 points. But United have spent much of the season lurching from crisis to crisis.
With a little more than a month on the season left, they are in severe danger of missing out on a place in next year's Champions League.
They could even miss out on a place in Europe all together if they can't finish at least sixth in the table and book a spot in the qualifying rounds of the Europa League.
Moyes has had to endure a series of lows during his first season at Old Trafford.
Here, in chronological order, is a list of his worst days.
Feel free to use the comments section below to add your own.