Towards the end of last season, McTominay was handed his debut at Arsenal and the 21-year-old has since gone on to make 19 appearances for the Premier League giants.
Nine of those outings have come since the start of 2018, and the youngster has admitted that he is keen to repay the faith shown in him by the Portuguese.
McTominay told The Mirror: "Obviously, there are numerous different factors that have contributed in terms of my development but the main one is Jose Mourinho.
"He's had the faith to put me in for important matches and trusted me in really big games. So all credit goes to him. If it wasn't for him, I wouldn't have had chances to play and show people I'm hopefully capable of being a Manchester United player in the future.
"There's nothing better for me than being selected in the big games. The Champions League game at Sevilla, the Champions League game before that, Liverpool, Chelsea and even the other cup games as well. It's really good for me to be trusted by the manager. I hope to repay him as he's done really well to push me forward."
McTominay could feature when United play host to Brighton & Hove Albion in the FA Cup quarter-finals on Saturday evening.