Judges of the Milan Court of Appeal confirmed the sentence for both Robinho and one of his friends for group sexual violence dating back to January 2013.
The pair were among a group of six men accused of taking part in the gang rape of a 22-year-old Albanian woman in a Milan nightclub.
They were both ordered to jointly pay the woman damages of 60,000 euros ($A97,000).
The case against the four other accused has been suspended.
Robinho was playing for AC Milan at the time of the attack and was tried in absentia in November 2017.
Television channel Globo Sports released excerpts of a recording Italian prosecutors used to secure their conviction, in which the player purportedly says, “I’m laughing because I don’t care. The woman was completely drunk. She doesn’t even know what happened.”
Robinho, 36, who has denied the charges, has the right to again appeal the nine-year sentence within 90 days.