A press conference is expected to be scheduled tomorrow morning in Chicago.
Thomas, 41, played for the White Sox from 1990-2005 and split the rest of his career between the Toronto Blue Jays and Oakland Athletics. He did not play last season, but served as an analyst for select games on Comcast.
With his retirement, Thomas will become eligible for the National Baseball Hall of Fame in 2014. His impressive resume includes 521 career home runs, which places him 18th on the all-time list. The five-time All-Star will also retire with a career batting average of .301.