According to Spanish sports newspaper Marca, the Real Madrid forward admitted to being a hands-on father.
"Of course I change [his] nappies. It's not the thing I like best in the world, but I do it," the star reportedly said.
The captain of the Portuguese national side also revealed that he hopes his son will consider a career in football one day.
"I would love him to like football, for him to be my successor, but we'll see what happens," he added. "My son will be whatever he wants."
Ronaldo's mother and sisters are helping him to raise his son Cristiano Ronaldo Jr, who was born last July.