Chiefs trainer Rick Burkholder told reporters Tuesday that Poe underwent surgery on a herniated disc in his back on July 15. Poe is out indefinitely.
Poe suffered a back injury during minicamp and reinjured it prior to undergoing surgery.
The loss of Poe is huge for a Chiefs defensive front that struggled to stop the run last season, finishing 28th in the NFL.
Poe compiled a career-high six sacks in 2014 and his game film displayed vast improvements after a slow start to his career.
The Chiefs exercised his fifth-year option in the offseason, keeping him with the team through the 2016 season. How much of the 2015 year he'll see remains to be seen.