Floyd sought multiple opinions on the injury, hoping major surgery could be avoided, but he received bad news every step of the way.
Not only will Floyd have surgery on the tear in his flexor muscle near his right elbow, but he also will have his ulnar collateral ligament repaired. Recovery time is expected to be anywhere from 14 to 19 months.
Floyd, 30, is in the final season of his contract with the White Sox and might have made his last pitch with the team. He was 0-4 with a 5.18 ERA in five starts this season. He is 63-65 in seven seasons with the White Sox, posting a 4.22 ERA.
His best season came in 2008 when he went 17-8 with a 3.84 ERA and went 200 innings for the only time in his career.
The right-hander was one of just four pitchers in the American League to reach double digits in victories in each of the past five seasons. He joined the Detroit Tigers' Justin Verlander, the Los Angeles Angels' Jered Weaver and James Shields, formerly of the Tampa Bay Rays and now of the Kansas City Royals, in that category.
Since 2008, Floyd had the fifth-most victories in the AL with 62, and also was fifth in starts with 153. He was sixth in both quality starts (86) and innings pitched (948 1/3), while ranking seventh in strikeouts with 754.
Floyd made his major league debut in 2004 with the Philadelphia Phillies. Since that first outing he is 70-70 in 10 seasons with a 4.48 ERA.
The White Sox are without two starters, but John Danks is expected to return later this month after undergoing shoulder surgery in August.