He attended Iowa Western Community College and Armstrong Atlantic State University.

He played one game for the Gulf Coast League Reds and 16 for rookie-class Billings in '07, going a combined 3–2 with a 3.24 ERA in 17 relief appearances.

[2] Horst made his debut on May 28, 2011, in relief of Bronson Arroyo against the Atlanta Braves.

In total, Horst pitched 2.2 innings, giving up 2 hits and one run, walking 0 and striking out 4.

On June 28, Horst and Brian Sanches were called up after Chad Qualls was Designated for Assignment and Joe Savery was optioned to Triple-A Lehigh Valley.

[9] In January 2015, Horst signed a minor league contract with the Los Angeles Dodgers[10] and was assigned to the AA Tulsa Drillers to start the season.

[11] He was named to the mid-season Texas League all-star team after producing a 1.64 ERA in 32 games with nine saves.

On March 15, 2016, Horst signed with the Somerset Patriots of the Atlantic League of Professional Baseball.