Ronaldo has thanked well-wishers after being discharged from hospital in Ibiza.
The former Brazil, Real Madrid and Inter star was admitted while on holiday after suffering from a bout of "strong flu".
The 41-year-old, a two-time winner of the Ballon d'Or, paid tribute to the hospital staff who treated him after initially playing down concerns he had a serious case of pneumonia.
In a statement posted on his official Twitter page, Ronaldo said: "Hi all! I'm home after a few days at the clinic. Thank you all for the affectionate comments and positive energy. Thanks to the team of doctors and nurses.
"Now let's focus on football! This season is going to be awesome."
Ronaldo won two World Cups and scored both his country's goals in the 2002 final triumph over Germany.