|Date of birth||October 25, 1985|
|Place of birth||Pine Grove, Pennsylvania, United States|
|Height||6 ft 4 in (1.93 m)|
|Real Salt Lake|
|2004–2007||Old Dominion Monarchs|
|2006||Virginia Beach Submariners||14||(1)|
|2007||Hampton Roads Piranhas||16||(0)|
|2008–2010||Real Salt Lake||3||(0)|
|2009||→ Austin Aztex (loan)||10||(0)|
|2010||→ Puerto Rico Islanders (loan)||24||(3)|
|2017–||Real Salt Lake||0||(0)|
|* Senior club appearances and goals counted for the domestic league only and correct as of November 8, 2016.
College and amateur
Horst played college soccer at Old Dominion University, and in the USL Premier Development League with Reading Rage, Virginia Beach Submariners and the Hampton Roads Piranhas. He was 2007 PDL Defensive Player of the Year.
Horst was drafted in the first round (14th overall) of the 2008 MLS SuperDraft by Real Salt Lake. He made his full professional debut for RSL on 16 August 2008 against the Houston Dynamo. Horst also spent time with USL-1 club Austin Aztex during the 2009 season.
During April 2010 Horst was sent out on loan to the Puerto Rico Islanders of the USSF Division 2 Professional League. He was sent off on his Islanders debut, on May 26, 2010 in a game against the Carolina RailHawks. On September 30, 2010, the Islanders where down 0-2 on halftime in a CONCACAF Champions League group stage match against Toluca from Mexico, teammate David Foley scored the first goal for the Islanders to make 2-1 in the second half, later, Horst scored the equalizer and the game winner in extra time. On October 2, 2010, Horst scored his first league goal against Miami FC. The Puerto Rico Islanders won the USSF Division 2 Professional League Championship on October 30, 2010 against the Carolina Railhawks.
On November 24, 2010, Horst was selected by Portland Timbers in the 2010 MLS Expansion Draft. Horst impressed during the Timbers' inaugural 2011 season and signed a new contract with the club on November 28, 2011.
On December 17, 2013, Horst was dealt to the Houston Dynamo in exchange for a 4th-round pick in the 2014 MLS SuperDraft. Due to an ankle injury to former Portland teammate Eric Brunner, Horst has become a starter for Houston. He has become a fan favorite for his tenacious tackling and fiery nature.
Puerto Rico Islanders
- USSF Division 2 Pro League Champions (1): 2010
- PR Islanders FC (2010-04-01). "En realidad, es Real el acuerdo" (in Spanish). Puerto RIco Islanders FC. Retrieved 2010-04-02.
- PR Islanders FC (2010-04-02). "El defensa David Horst a los Islanders" (in Spanish). Puerto RIco Islanders FC. Retrieved 2010-04-02.
- "Archived copy". Archived from the original on 2011-11-30. Retrieved 2011-11-28.