Mourinho replaced van Gaal, who was sacked by the club following a disappointing fifth-placed finish in the Premier League during the 2015/16 campaign.
The 20-year-old was left frustrated under the the Dutchman after he stopped his loan move in January and promised to give him more playing time.
Speaking about Mourinho, he claims he would love to work under him and will be ready to play.
“We look forward to working with him and are very happy too,” he said.
“Mourinho he is a great coach, I’m prepared to work with him and make a great season.
“I’ll do my best to play and be ready.”
He only made 11 appearances under van Gaal and played a total of just 43 minutes following the close of the winter transfer window. He may have been furious, but the arrival of Mourinho should be a second chance for players like Pereira to work hard and cement their place on the first-team.
Pereira is highly rated by United fans and coaches but has rarely been given a chance to show what he can do in the senior side. With Mourinho coming in his future at Old Trafford looks uncertain but we all saw what happened when Paul Pogba left for free in 2012 to join Juventus.
A loan move would be beneficial for his development if he won’t get any game time because he definitely deserves more opportunities and has proven his ability plenty of times on the centre stage. I’m pretty sure most fans still remember his free-kick against Ipswich Town on his senior debut. Beautiful.