His introduction into the entertainment industry began in 2003, when he made his film debut in Secondhand Lions, alongside his brother Marc. Haley Joel Osment, the actor who portrayed Walter in Secondhand Lions, is the brother of Emily Osment. Both Musso and Osment now co-star together on the Disney Channel sitcom, Hannah Montana. Before Musso was cast in Secondhand Lions, he had been in several films beforehand: Am I Crushed? as Richie and The Keyman as a cub scout both in 2002.
Musso recorded a remixed remake of the song "Lean On Me" for the Disney film, Snow Buddies; the music video is included on the DVD and the song is included on the Radio Disney Jams 10 CD. Musso also sang the song "If I Didn't Have You" with Hannah Montana co-star Emily Osment for the DisneyMania 6 CD. For their 2009 Disney Channel Original Movie, Hatching Pete, Musso teamed up with co-star Tiffany Thornton, from Sonny With A Chance, to record a song called "Let It Go" that was used in the film. The two also worked on a music video for the song which was released to Disney Channel. Musso also record a song called "The Girl Can't Help It" for another Disney Channel Original Movie, Princess Protection Program. "Let it Go" and "The Girl Can't Help It" will be on the Disney compilation album, Disney Channel Playlist, which will be released on June 9, 2009.
In a studio effort, Musso released his self-titled debut album on June 2, 2009. His debut single, "The In Crowd," a cover of a John Hampson song, premiered on Radio Disney on December 5, 2008.
The song is also featured on Radio Disney Jams, Vol. 11.
His second single, Hey, was released on May 15 2009 on Radio Disney with an accompanying music video that premiered on Disney Channel.
