Williams' contract was selected by the White Sox on Thursday. He's starting in left field for Thursday's game against Kansas City.
The White Sox placed Billy Hamilton (hamstring) on the injured list Thursday, and Williams will take his place on the major-league roster. While Andrew Vaughn should see most of the playing time in left field in Hamilton's absence, Williams is getting the first crack at it, perhaps because righty Brad Keller is starting for the Royals.