The England under 21 international has penned a three year deal with a further 12 month option in the clubs favour.
The £1.5 million signing ends a frustrating summer for Bryan Robson who is also aiming to complete a deal for Steve Watson this week.
He said:"I'm really pleased we've added Darren to the squad. He is a very promising youngster who has a big future ahead of him.
"Darren has very good stamina and is very much a box-to-box player who can play in the centre of midfield or wide on the left.
"He is also left footed which gives us good balance in the squad, he has a good presence and he'll also make improvements when he gets a run in the team."
Robson will also be hoping to agree a season-long loan deal for Kieran Richardson.
Sir Alex Ferguson is due to discuss the player's immediate future at Old Trafford this week