Los Blancos opted to reappoint their old boss in July following two trophyless years at the Estadio Bernabeu.
Mourinho has been heavily backed in the summer transfer window - with a club record deal for Yan Diomande - alongside moves for Denzel Dumfries and Carlos Espi.
The core of the team from last season is expected to stay the same under Mourinho's leadership and Courtois is unchallenged as No.1.
The Belgian international ended the 2026 FIFA World Cup with a hip injury, which was confirmed as minor following a quick summer trip back to Madrid, and he's confident Mourinho can bring the glory days back in the months ahead.
"He's a very demanding coach who puts the team before the individual, which is important when it comes to winning trophies. He's a great coach.
"As a person, he's very approachable, he says things as they are, and I like that honesty; it's the direction we need to take. We were together at Chelsea and we won the Premier League. I have good memories of him and I'm happy to be working under him again.
"I want to win titles again; it's important for the team, the fans and the club. There are quite a few new players, and we know some of them from playing against them. We're eager to be all together again after the World Cup and fight for another great season."