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.
Kohn was drafted by the Angels in the 13th round of the 2008 MLB Draft out of the College of Charleston.
Kohn spent most of his collegiate career as a fielder, posting a .311 batting average with 93 RBI, 75 runs and 19 home runs in 315 at bats. He pitched part of his senior season and in 13 innings, had 16 strikeouts and only gave up three earned runs for a 2.08 ERA.