The surgery to reconstruct Kuhl's ulnar collateral ligament was performed by Dr. David Altchek in New York. The Pirates said pitchers typically return from the surgery in 14 to 16 months.
Kuhl said in a tweet that the decision to have the surgery was difficult but he is "confident moving forward that I'll be pitching" in the majors again.
Kuhl, 26, hasn't pitched since June 26. He was 5-5 with a 4.55 ERA in 16 starts this season.
He is 18-20 with a 4.37 ERA in 61 career starts for the Pirates.