The former Gold Glove winner waived his no-trade clause and his first game is expected to be on Friday when Atlanta travels to Chicago for a three-game series against Lee's former team mates at Wrigley Field.
Atlanta sent right-handed pitchers Robinson Lopez and Tyrelle Harris and left-hander Jeffrey Lorick to Chicago.
The Braves (70-49), who hold a 2.5 game lead over the Philadelphia Phillies atop the National League East division, hope Lee will prove more dependable than Troy Glaus, who appeared to further aggravate his troublesome knees during Tuesday's game.
Glaus has batted .175 with two homers over his past 45 games while Lee has batted .282 with six homers over a similar period and is considered a better defensive player.
For the season, Lee has 16 homers and 56 RBIs to go with a .251 batting average.
Chicago (50-71) is mired in fifth place in the NL Central, 19 games behind division-leading Cincinnati.
(Writing by Larry Fine, Editing by Frank Pingue)