The Frenchman had been continuously linked with a move back to Old Trafford, but finalised his £89 million transfer just four years after departing for Juventus.
Speaking about Mourinho, Pogba insists he was a key factor in his decision.
“I spoke with a lot of players when he was at Madrid,” he said.
“I spoke with Morata and I spoke with others and they all told me he’s the coach for me because he’s going to make you work harder. I feel this.
“I spoke with him a few times and he gave me energy and positivity. I was thinking ‘why not?’. I’m sure he can help me improve and make me a better player and a better person.”
Pogba won four consecutive Serie A titles during his time with the Italian club and returns to England as one of the best midfielders in the world.
He left due after growing frustrated with Sir Alex Ferguson, but will undoubtedly play a vital role on Mourinho’s exciting new United side.
It’s a staggering amount of money to play for one player, but Pogba will take the club to the next level and title contenders, if not favourites for this season.