The 47-year-old Dane's spot in the field will be taken American Kevin Streelman.
"Unfortunately having to WD from @PGAChampionship due to reoccurrence of my old back not holding up!!," Bjorn said on Twitter.
"Thank you to @PGA for having me this week and good luck everyone playing this week."
Bjorn also confirmed that he will remain at Bellerive Country Club to watch the year's final major starting on Thursday as he prepares to make his four captain's picks for the Ryder Cup to played next month in Paris.
(Reporting by Steve Keating, Editing by Ed Osmond)
