He also competed at the 2012 Summer Olympics in London, where he qualified for the horizontal bar event final and finished in sixth place.

In 2016, he had surgery on his left rotator cuff and as a result was unable to qualify for the 2016 Olympics in Rio de Janeiro.

Later that year he was chosen to compete for the United States at the Pan American Games in Santo Domingo where the men's team won bronze and he placed fourth all-around.

From 2005–08, Horton competed for the Oklahoma Sooners gymnastics team alongside his 2010 & 2011 world teammates Chris Brooks and Steven Legendre.

When competing for Oklahoma, he won 6 NCAA titles and 18 All-American honors, breaking the record previously set by Bart Conner.

That summer, he competed in the U.S. National Championships and won gold on the floor, silver in the all-around, and bronze on the horizontal bar.

He won his second consecutive American Cup All-Around title, the first male gymnast since Blaine Wilson to achieve the feat.

[6][7] In 2009, Horton became the U.S. National Champion and competed at the 2009 World Artistic Gymnastics Championships in London where he reached the finals in the all-around and on the horizontal bar.

He was selected for the 2010 World Artistic Gymnastics Championships in Rotterdam, where the U.S. team placed fourth, and Horton won the all-around bronze medal.

Although qualifying fifth all-around in the preliminary round, he was edged out by teammates Danell Leyva and John Orozco (only two athletes from each country were allowed to compete in individual event finals).

On returning home, it was discovered that the injury was worse than previously thought, with a torn ligament and two broken bones in a foot that would require surgery.

"[11] The team finished fifth, while Horton's best result in an individual event final was sixth place on the horizontal bar.

Horton became "the shortest man to ever make it to the top of the warped wall" as a walk-on to the Houston Qualifying course for Season 7 (2015).