The former Torino full-back is currently on international duty with Italy at Euro 2016 and had been linked with a move to Juventus this summer.
Reports suggest Mourinho intervened to ensure Juventus cannot complete a deal and has made it clear he will not be leaving Old Trafford.
He has been very unlucky with a series of injuries keeping him from reaching his full potential in his first Premier League campaign but it looks like he has impressed Mourinho.
Darmian hasn’t quite been able to replicate his form from the start of the season, for his first few games he was one of the best players on the pitch and proved to be an incredible investment, even winning United’s Player of the Month award for August.
As the campaign continued his form slipped and he was often switched around the back four making it hard for him to establish any sort of consistency.
I believe he’ll be a brilliant player under Mourinho and he’ll looking to put his head down and hit the ground running under the Portuguese boss at Old Trafford.