The 39-year-old, who also played for Barcelona and Inter Milan, said his compatriot reminded him of himself.
"I like Neymar a lot. He is a bit like me," he told Calciomercato (via Goal.com). "He had some difficulties in getting used to his new environment at first, but I knew that he was going to succeed."
Ronaldo anticipates Neymar to be the successor to five-time Ballon d'Or winner Lionel Messi at Camp Nou.
"Can he be Messi's heir? Yes, he has everything he needs to become as strong as him."
Ronaldo also spoke about the fortunes of his old club Madrid, who are now managed by his former team-mate Zinedine Zidane.
"Everybody knows that Zizou is a great friend," he said. "I really hope that he will have a great career as a coach too. He's the best player with whom I have ever played with. We had a lot of fun on the pitch."
He's expecting big things from Los Blancos under the legendary Frenchman.
"Could this be Real Madrid's year? Yes, they must focus on the Champions League, they have everything to succeed," he insisted. "Winning at Roma was very important for Zidane."
The La Liga giants are both in action this weekend, with Barcelona travelling to Las Palmas on Saturday afternoon and Real Madrid visiting Malaga on Sunday.