A Milan court ruled that Robinho and five other Brazilians assaulted the woman, who was 22 at the time, after plying her with alcohol in a discotheque. The whereabouts of Robinho's five companions is not known, so their trial has been put on hold.
Robinho, 33, who currently plays with Atletico Mineiro in Brazil, pleaded not guilty via his lawyer and never appeared at any of the court hearings in northern Italy.
He has a right to two appeals and Italy would only launch extradition proceedings once this legal process is exhausted, a legal source said.
The Milan court ordered the victim to receive 60,000 euros ($71,000) as compensation for her suffering.
Robinho, who also played for Real Madrid and Manchester City, has made 100 appearances for the Brazil national team and scored 28 goals.