The Warriors announced the deal Wednesday. Terms of the contract were not disclosed.
Barbosa appeared in 20 games with the Phoenix Suns last season. He averaged 7.5 points, 1.9 rebounds, 1.6 assists and 18.4 minutes per game.
He spent the first part of the year playing in his native Sao Paulo in the Brazilian League. Barbosa also played for Brazil in the FIBA Basketball World Cup before signing with the Warriors.