The alleged incident occurred in January 2013, when the Brazilian was playing for Milan in Serie A.
He was found guilty in absentia by an Italian court for raping a 22-year-old Albanian woman.
Five of the player's friends were accused of the same crime. One of the accused was also given a nine-year prison sentence while the trial of the four others has been suspended because they are on the run.
According to Milan daily Corriere della Sera, Robinho and his acquaintances made the young woman drink “to the point of making her unconscious and unable to resist”.
They were then said to have engaged in “sexual intercourse multiple times in a row” with her.
The court in Milan also ordered those found guilty to pay the victim €60,000.
Robinho, who is currently playing for Atletico Mineiro in Brazil, posted messages on his Instagram and Facebook profiles protesting his innocence and his lawyer said an appeal against the verdict had been launched.
“We have already said that he has defended himself against these accusations and stated that he played no role in this incident,” the statement said.
“All legal measures have already been taken.”
The sentence is suspended while appeals take place.
It is not the first time the player has faced allegations of sexual misconduct.
He was questioned by British police in 2009 after a woman accused him of assault at a nightclub in Leeds, northern England, while he was playing for Manchester City. He was eventually released without charge.
The 33-year-old won 100 international caps for Brazil and played in the 2006 and 2010 World Cups.