Ronaldo played for PSV, Barcelona, Inter, Real Madrid and AC Milan throughout his career and also enjoyed success with Brazil's national team.
Benzema has revealed his huge admiration for the World Cup winner and still watches videos of him in order to try and improve his own game.
"When I was younger, the way the Brazilian Ronaldo played had an influence on me," the 81-cap France forward told the Bwin website.
"For me he's the best striker and the best player of all-time.
"I watch videos of him, and try to do what he does, but it's not easy. It's impossible to pull off the same moves as he did."
Benzema has been embroiled in controversy this season, charged as part of the investigation into an alleged sex tape blackmail plot aimed at his fellow international team-mate Mathieu Valbuena.
Having been suspended indefinitely from France duty, he faces the prospect of missing Euro 2016 on home soil later this year.
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"He was a top player and now he's a good coach, with a lot of experience," he said.
"He offers the team a lot, he gives us confidence, gives us his ideas on how to play, and that's all positive for us.
"My team-mates and I are learning from him every day because we know that he was a great player, and that he knows a lot about the game."
Madrid are preparing for the first leg of their Champions League round-of-16 tie with Roma on Wednesday and Benzema is confident they can get a good result at the Stadio Olimpico.
"They'll be going out to get the win, because for them it's an important game and they're at home," he said.
"We'll also be going there to win because we know that the first leg is very important if we want to get through the tie, although there is always the home leg to follow. We're going to work hard to win the game.
Meanwhile, Madrid have been boosted by the news Marcelo has shrugged off a shoulder injury and has returned to the squad for Wednesday's match.