The 20-year-old World Cup winner was bought from Monaco for a fee of £166m, making him the second-most expensive player in history behind team-mate Neymar.
And his stock has risen ever since switching clubs in Ligue 1, with the France international truly one of football’s elite already.
Mbappe was named fourth in the 2018 Ballon d’Or listings, behind Luka Modric, Ronaldo and Antoine Griezmann, while Messi trailed him in fifth.
Real Madrid continue to be linked with a move for PSG’s No.7, but prising him away is proving near impossible.
As a result, the La Liga giants have focused their attention on Chelsea’s Eden Hazard ahead of the summer.
Mbappe is expected to front the next generation, with Ronaldo and Messi coming towards the latter stages of their playing careers.
Ronaldo, who was bought by Juventus from Real for around £100m last year, turned 34 in February, while Messi will be 32 come June.
Mourinho’s comparison between Mbappe, Messi and Ronaldo comes as:
“Just focus on now. He’s absolutely incredible”Jose Mourinho.
Mourinho managed Ronaldo at the Bernabeu and is a huge admirer of Messi too, with both players scoring hat-tricks for Juventus and Barcelona respectively last week.
But Mbappe’s quality now on top of his promise for a huge career makes him the more valuable financially now for ex-Manchester United manager Mourinho.
The Portuguese told beIN SPORTS: “For a player like Mbappe, when you speak about the future, you don’t need to say what he’s going to be like in five years’ time, in 10 years’ time.
“Just focus on now. He’s absolutely incredible. Jose Mourinho.
“I think going by his age and [considering] the age of Cristiano, of Messi, [both] over 30, Neymar is 27…
“When you go to the market level and age is also a factor, I think he’s the most valuable player in the world.
“In a hypothetical transfer, he’s the most expensive player in football now.”
While Mbappe’s PSG were dumped out of the Champions League by Mourinho’s old club United, Messi’s Barcelona and Ronaldo’s Juventus could still face one another come the final in an ultimate rare showdown, with the pair no longer plying their trade in the same country.
Juventus face Ajax in the quarter-finals and would then need to beat either Manchester City or Tottenham, while Barcelona await a tie with United and then either Liverpool or Porto in the semi-finals.