The Brazilian and Real Madrid legend, speaking from the stands where he has been watching the national team at the tournament, also offered words of praise for Lionel Messi, acknowledged that all records are made to be broken, and backed Zinedine Zidane as the ideal candidate to one day manage France.
"Messi is one of the best players in the history of football and continues to be influential and decisive today," Ronaldo said.
"As for Mbappé, his style of play reminds me of my peak. He is one of the greatest in football today and a natural heir of the legends of the game."
On the subject of Messi and Mbappé having surpassed his own World Cup goal tally, Ronaldo was philosophical.
"All records are there to be broken," he said, "but this doesn't erase the legacy a footballer leaves."
Ronaldo was effusive in his praise for Brazil coach Carlo Ancelotti, whom he considers the ideal man for the job.
"I have tremendous confidence in Ancelotti's work and his ability to calm the atmosphere and get the best out of his players," he said. "He understands football like few others and knows how to manage pressure. I would not choose any other coach now for the Seleção."
On Neymar's inclusion in the squad, Ronaldo backed the decision strongly.
"I was in favour for a good reason: Neymar is decisive," he said. "I don't see another player in the current group with the same ability as him to win a match. So if we could count on him, we should not miss the opportunity. He has the doctors' permission, he is in good physical shape and now has the opportunity to silence all those who did not believe in him."
Ronaldo also offered an endorsement of Zidane as a future France manager.
"I have always said he has the perfect profile for this position," he said. "He has talent, experience, tactical intelligence and the ideal character. And it is not just an instinct I give you — he has already proved it with his brilliant work at Real Madrid."
Brazil, France, Spain and Argentina are Ronaldo's picks as tournament favourites, with Germany also mentioned as a dangerous side.