Mourinho arrived at Los Blancos in 2010 - a year after they had broken the bank to sign Ronaldo from Manchester United in a record-breaking £80million deal.
Eyebrows were raised over the astronomical fee at the time, but if one player justified breaking that ceiling, it was Ronaldo.
In his debut season at Real, the Portuguese star was an instant hero as he chipped in with 33 goals in all competitions.
However, after Mourinho arrived, Ronaldo's game propelled into the stratosphere - scoring 53 times the following campaign - then 60 the next and 55 the year after that.
Talking to Ronaldo's ex-United teammate Rio Ferdinand, on his YouTube channel Five, Mourinho explained the secret to getting the five-time Ballon d'Or winner to perform.
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"Motivation, you don't need to give him. Ambition, responsibility, you cannot give him. Technically, you cannot give him," the 61-year-old said, who managed Real for three years.
"It's just to give him some tactical adjustments and let the guy be happy."
And despite managing some of the biggest egos in world football throughout his career, the Special One has insisted he was happy for Ronaldo to do his own thing.
He remarked: "I think you don't coach. I don't have to teach much, it is about being happy, it is about creating an environment by the tactical point of view, by the idea of football where the player can show his best.
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"I think Madrid, for him, was a little bit of a transition because for you, he was a winger.
"Right winger, left winger, out wide, dribbling, attacking people, beating people.
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"In Madrid, he became more the goalscorer he was for the rest of his career.
"In fact, probably the first time he played as a striker in a big match was Real Madrid vs Barcelona in the cup final where he scored an amazing goal, an amazing header in extra-time.
"Probably that was the beginning of people having a feeling that animal could be a goalscorer and not just a pure winger.
"Madrid was a little bit of that, a little bit hybrid because he was playing from the left but he was not wide and he was not chasing full-backs.
"We were protecting him with the balance that we were giving behind with Xabi Alonso and Sami Khedira."
As the case for many of Mourinho's jobs, his relationship broke down with the club and players and he left at the end of the 2012/13 season having brought LaLiga and Copa del Rey success to the Bernabeu.
Much was made of dressing room fractures at the club where there were reports Mourinho had fallen out with key players such as Sergio Ramos and Iker Casillas, who he sidelined in 2013.
He even had choice words for Ronaldo at the time, as Mourinho stated: "Maybe thinks that he knows everything and that the coach cannot improve him anymore."
And after Mourinho joined Chelsea in 2013, he was asked about his relationship with Ronaldo.
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To which he said: "The relationship does not exist. He plays for Real Madrid and I'm at Chelsea. You would not find us hanging around together."
While Ronaldo and Mourinho won silverware together, Real fans would have been hoping they'd have enjoyed Champions League success.