Memphis had his attitude questioned after being pictured having nights on the tiles and is better known for his flash cars than his football.
But Mourinho said: “You can see him driving a nice car and you think this guy is not thinking about football.
“But that is not the case.
“The kid thinks about football, the kid suffers because he is frustrated with what happened last season where he lost all his confidence.
“But he will be back. I see a good boy, a good kid, a good professional. I don't care what people think.
“Of course I want him to be part of my squad. Last season was last season and I don't want to go into that too much but I know the players I've watched.
“At the World Cup he was a very young kid and that was two years ago.
“I know the player and I watched him many times at PSV and having that player in mind, I want to keep him.
“I want to try everything and the way he is working is so good that for sure, we all believe that is possible."
Depay, 22, will need to wait a month before United's fixture list means he will get a chance.
Mourinho added: “I know that you look to the last match and he was not on the bench, I had Rashford, Mata and Mkhitaryan on the bench for these positions.
“But in September we have Capital One Cup, Europa League and Premier League so that month will be the end of the frustration for these players that are not selected in these first two or three matches.
“September is the moment when everyone is playing and life changes for them.
“But I believe in him, yes. The players are never happy when they are not playing.
“There are always words and words and words but the reality is that no player is happy when he is not playing."
Man Utd boss Mourinho has special message for doubting Memphis.. - written by Ogundokun Ayobami , published at 16:40 . And have 0