White Sox general manager Rick Hahn said the addition of Jackson gives manager Robin Ventura more flexibility on offence and defence. The team announced the move Sunday night after Jackson completed a physical.
"We’re a better team tonight than we were this morning," Hahn said in Glendale, Arizona.
Hahn said Jackson will be in camp Monday morning, though it might be a week before he plays in a regular spring training game.
Jackson played for Seattle and the Chicago Cubs last season, batting .267 with nine homers and 48 RBIs in 136 games. He is a .273 hitter with 55 homers, 296 RBIs and 106 steals in 860 career games.
The 29-year-old Jackson has played mostly centre field during his six seasons in the majors. The returning White Sox outfielders are Melky Cabrera in left, Adam Eaton in centre and Avisail Garcia in right, plus reserve J.B. Shuck.
"Most of, if not all of, Austin’s time will come in centre," Hahn said. "We also view Adam as a very fine defensive centre fielder. Adam’s expressed a willingness to do whatever we need that day. We’ll let the lineups take care of themselves."
Eaton is coming back from shoulder surgery and is serving as a designated hitter in the Cactus League, though he is expected to be ready for opening day. Garcia hit .257 with 13 homers in his first full season in the big leagues.
In addition, Adam LaRoche — who shares time at first base and designated hitter with Jose Abreu — is currently out with back spasms. After a season in which LaRoche hit .207 with 12 homers, using one of the outfielders as a DH at times is a possibility, Hahn said.
"Nothing has been promised to anybody," Hahn said about playing time. "When it comes to making out the lineup, Robin’s mission is to put the best lineup in position to win that ballgame.
"We still believe Avi is going to blossom into being the player many people believe he can become."
The move returns Jackson to the AL Central after he made his major league debut with Detroit in 2010. He played for the Tigers for four-plus seasons before he was traded to Seattle in a 2014 deadline deal that moved ace David Price from Tampa Bay to Detroit.
To make room for Jackson on the 40-man roster, the White Sox designated third baseman Mike Olt for assignment.