Kohn made his major league debut on July 26, 2010, against the Boston Red SoxatAngel Stadium of Anaheim.[2] He finished the season appearing in 24 games, going 2-0. In 2011, Kohn struggled with control, walking 9 in 12.1 innings and allowing 10 runs. He spent the entire 2012 season on the disabled list due to Tommy John surgery.[3][4] Fully healthy in 2013, Kohn was a bullpen mainstay for the Angels, appearing in a career high 63 games. On September 2, 2014, Kohn was designated for assignment.[5] On September 8, 2014, Kohn chose free agency rather than accepting a demotion to the minors.[6]
On December 4, 2014, Kohn was signed to a minor league deal by the Atlanta Braves, a deal that included an invite to Spring Training.[9][10] He was sent to minor league camp on March 30, 2015, and began the season with the Gwinnett Braves.[11] On April 24, Kohn was recalled[12] and made his Braves' debut two days later.[13] He became a free agent on October 5, 2015.
On July 21, 2017, Kohn signed a minor league deal with the Minnesota Twins.[14] He spent the year split between the rookie–level Gulf Coast League Twins, High–A Fort Myers Miracle, and Triple–A Rochester Red Wings. In 13 appearances between the three affiliates, Kohn logged a 1.38 ERA with 18 strikeouts across 13.0 innings pitched. He was released by the Twins organization on March 25, 2018.[15]
On February 8, 2019, Kohn signed a minor league contract with the Arizona Diamondbacks.[16] He made 27 appearances split between the rookie–level Arizona League Diamondbacks, Double–A Jackson Generals, and Triple–A Reno Aces, accumulating a 4.03 ERA with 50 strikeouts and 9 saves. Kohn elected free agency following the season on November 7.[17]
On February 1, 2020, Kohn signed a minor league deal with the Los Angeles Angels. Kohn did not play in a game in 2020 due to the cancellation of the minor league season because of the COVID-19 pandemic.[18] He became a free agent on November 2.
On March 25, 2021, Kohn announced his retirement from professional baseball on Instagram.[19]
