The 'Red Solo Cup' singer announced on his website that he would be "undergoing a minor medical outpatient procedure" this week.
The operation has been named as gall bladder surgery, E! Online reports.
The news means that Keith's Fort McCoy gig has been delayed from Thursday (August 2) until August 30, though Gretchen Wilson will still appear at this week's concert.
Meanwhile, a spokesperson for Keith claimed that he is recovering well after the operation yesterday.
Tickets purchased for Thursday's performance will be accepted on the new date, while Keith's website confirmed that this is the only appearance that will be affected.
"The 'Live in Overdrive' tour will resume on August 3 at the WE Fest in Detroit Lakes, MN," the message read.
It recently emerged that Keith was asked if he would like to join the American Idol judging panel but decided to turn down the offer.