The Angels made the announcement on Wednesday after Kohn visited orthopedist Dr. James Andrews. Kohn is scheduled to have the surgery on Thursday.
Kohn was shut down with elbow discomfort in spring training, but started a throwing program last week in hopes of making a prompt return. But when the pain persisted, Kohn visited Andrews for a second opinion and was diagnosed with the torn elbow ligament.
The 25-year-old Kohn spent most of last season with Triple-A Salt Lake. He went 0-1 with a 7.30 ERA and one save in 14 appearances for the Angels. He's made 38 relief appearances in two seasons with the Angels.