The Portuguese footballer, who currently plays for Real Madrid, said that he would like to meet Obama and praised his people skills.
"I like the way he speaks with people, his communication," Ronaldo told CNN.
"I think it's always firm what he says - and I would like to meet him because he's an honest person."
Ronaldo's former Manchester United teammate Wayne Rooney has previously revealed his support for Obama, writing on Twitter: "Watched all the presidential debates. If I had to vote would vote Obama."
Fellow Englishman Piers Morgan quipped in response: "Game-changing endorsement."
Celebrities backing Barack Obama - photo gallery: