He was replaced in the field by Sean O’Hair, who will be making his ninth PGA appearance.
DeLaet, No. 89 in the Official World Golf Ranking, injured his left thumb two weeks ago at the Canadian Open.
“So disappointed that I can’t tee it up at the PGA,” he tweeted. “Need some time for my body to heal. I plan on being back and ready for a playoff run.”
This is O’Hair first major since the 2012 PGA. He has missed five of his last six cuts.
On Sunday, two more players earned a tee time at Whistling Straits: alternate Martin Laird got a spot because WGC-Bridgestone Invitational winner Shane Lowry was already in the field, and J.J. Henry secured the final berth after winning the opposite-field Barracuda Championship.