The 2017 PGA champ also missed the Wells Fargo Championship two weeks ago with the same injury. He tied for 12th last month at the Masters.
"I've seen too many people come back too early,'' Thomas told The Associated Press prior to the PGA Championship. "I plan on doing this successfully for a long time, and I don't want a dumb decision to set me back.''
Thomas injured his wrist and shoulder when he hit a tree while trying to hit a shot at the Honda Classic in March.
Ranked fifth in the world, Thomas, 26, has nine career PGA Tour victories. His best result this season was second at the Genesis Open in February. He also finished third in the Waste Management Phoenix Open and the Sentry Tournament of Champions.
ESPN's Bob Harig and The Associated Press contributed to this report.