Thomas, 41, earned American League MVP honors twice during his tenure with the White Sox and, during his 19-year career, was considered one of the game's foremost sluggers.
Drafted by the White Sox with the seventh overall pick in 1989, the Auburn product made his big league debut just over a year later, and in 1991, his first full season, he finished third in the AL MVP voting.
During his career, spent with the White Sox through 2005 and then with the Athletics and Blue Jays over the next three seasons, Thomas hit .301 with 521 home runs, 1,704 RBIs, 1,494 runs scored and 495 doubles while drawing 1,667 walks in 2,322 games.
A five-time All-Star, he was just the 11th player in big league history to win back-to-back MVP awards, winning in 1993 and 1994.
Thomas holds the franchise record in several offensive categories as well, including home runs (448), doubles (447), RBIs (1,465), runs scored (1,327), extra-base hits (906), walks (1,466), total bases (3,949), slugging percentage (.568) and on-base percentage (.427).
Along with Hall of Famers Mel Ott, Babe Ruth and Ted Williams, Thomas is one of just four players in baseball history to have a .300 average with 500 home runs, 1,500 RBIs, 1,000 runs scored and 1,500 walks in his career. He is a four-time Silver Slugger Award winner (1991, 1993, 1994, 2000), and he was named the 2000 AL Comeback Player of the Year.
Thomas announced his retirement Thursday while receiving a Lifetime Achievement Award at the Comcast SportsNets Awards ceremony benefiting the March of Dimes.
"I am officially retired. It's time. It's in my heart, and it's time to move on," Thomas said. "I'm proud to say I'm ready to retire. I enjoyed a wonderful career and have nothing left to prove. It's a young man's game now."
Thomas becomes the 10th player to have his number retired by the White Sox. His No. 35 joins Nos. 2 (Nellie Fox), 3 (Harold Baines), 4 (Luke Appling), 9 (Minnie Minoso), 11 (Luis Aparicio, though it has been un-retired for the 2010 season for veteran shortstop Omar Vizquel), 16 (Ted Lyons), 19 (Billy Pierce), 42 (Jackie Robinson) and 72 (Carlton Fisk).
Lisa Winston is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.