De Aza, 30, hit .243 with five homers, 31 RBIs and 15 steals in 122 games with the White Sox this year. He made his major league debut with the Marlins in 2007 and is a .268 career hitter with 35 homers and 179 RBIs in seven seasons.
Baltimore sent minor league right-handers Mark Blackmar and Miguel Chalas to Chicago to complete Saturday's trade.
Blackmar went 10-1 with a 3.18 ERA in 26 games with Class A Frederick. Chalas, also 22, had a 3-4 record and a 4.48 ERA in 30 combined relief appearances between Frederick and Triple-A Norfolk.