[citation needed] Horner discovered a love for acting after appearing in school productions of A Midsummer Night's Dream and The Maids.

Horner has appeared in various TV programs since 2001 – as Jackson in Cybergirl, as Jesse Spencer's character's brother in Swimming Upstream, as a reporter on Totally Wild, and as Caleb in the U.S. series Monarch Cove.

He starred as Richard Cypher in Legend of the Seeker – the syndicated television adaptation of Terry Goodkind's Sword of Truth book series.

He was a member of the band 'Earth For Now' (known as 'Unstable Conditions' in 2011) who played their first show in Hollywood, California, starting the set with "Howl at the Moon".

Horner also enjoys playing soccer, volleyball, tennis, swimming, skiing, snowboarding, and kayaking.