Frank De Boer allegedly plans to make the 19-year-old a first-team regular at Selhurst Park as he looks to pick up some more experience.
He will be their third signing of the summer following the captures of Jairo Riedewald and Ruben Loftus-Cheek.
Fosu-Mensah has made 21 appearances since his debut in February 2016, but Jose Mourinho is a big fan of his game and even secured him a long-term contract extension last season.
The Portuguese boss has been unable to offer him regular game time at Old Trafford, which is why he has sanctioned a temporary move to Palace.
He’s highly versatile and is capable of playing in central defence or at wing-back and has also previously been utilised in a defensive midfield role.
There’s a big future for Fosu-Mensah ahead at United and he’s already showcased, with games against Tottenham Hotspur last season where he completely held the game together, just for us to concede three goals as soon as he was taken off the pitch for Matteo Darmian, that he has an amazing ability to control games.
He could be in contention to start for Palace in their first game of the season against newly-promoted Huddersfield on Saturday.