In 2010, Horn won on Jeopardy! during Kids Week, earning $31,800 after wagering $12,000 during Final Jeopardy! Producer Scott Rudin was among those viewers impressed by Horn, subsequently offering him an audition for the role of Oskar Schell in Extremely Loud and Incredibly Close. Horn's performance in the movie was praised by critics "for its sensitivity and emotional depth".
After EL&IC and Space Warriors, Horn returned to being a student at Piedmont High School. In 2014, Horn was studying at UCLA and was described as a strong student who plays classical piano and is active in dance. Horn said that he still auditioned and wanted to pursue acting further but was continuing his studies as a backup plan.
