The 21-year-old, who has made 13 first-team appearances for Man United, spent the 2016-17 campaign on loan at Granada.
The former PSV Eindhoven youngster scored five times in 37 appearances during an impressive spell in Spain, and he is now looking to make an impression at Old Trafford after returning to his parent club.
"I think I'm ready now," Pereira told Man United's official website. "I have played over 2,000 minutes now in men's football, in La Liga, and I did quite well. I feel I'm ready, more than ready, to play men's football now.
"I am more mature as well, physically and mentally, and I am ready to come back and hopefully push to play next season for United. I played out wide in the beginning then, after that, I played more as a no.10 and, then in the last two or three months, I've played as a central midfielder.
"It went well and I think I have found another position. I think it's good to be more of an all-round player and Granada have used me in every midfield position.
"So I am happy the coach trusted me and I did my job. It's important but, as always, I will go where the manager needs me, I will play in any position and feel I can fulfil many roles."
Under Louis van Gaal, Pereira scored once in 11 appearances for Man United during the 2015-16 season.