Career
Gallagher began acting at the age of two, modeling for print advertorials in and around New York City, which eventually led to commercial work as an actor. As a toddler, he appeared in several television commercials for products such as Tyson Foods and Fisher-Price. When he was eight years old, he had a recurring role on the soap opera Loving.
Gallagher made his film debut in 1993 portraying Mikey Ubriacco in the film Look Who's Talking Now!, and in 1995 was part of a production of A Christmas Carol on Broadway. He also starred in several television films, including Bermuda Triangle.
In 1996, Gallagher co-starred with John Travolta in the film Phenomenon as Al Pennamin. Later that year, he was cast as Simon Camden in 7th Heaven, which aired for eleven seasons, making it the longest-running family drama on television, and became the highest-rated series on The WB.
During hiatuses from filming, he appeared in several films, including the direct-to-video Richie Rich's Christmas Wish and Little Secrets with Evan Rachel Wood. In 2003, during 7th Heaven's eighth season, Gallagher left the show to attend college full-time. However, he returned to the series part-time during the ninth season and the tenth season, which was thought to be the final season. In late 2006, The CW renewed 7th Heaven for an eleventh season, but Gallagher chose not to renew his contract. In 2005, Gallagher starred in and co-produced a low-budget adaptation of The Picture of Dorian Gray.
After leaving 7th Heaven, he had several roles, including serial killer Buck Winters in Numb3rs, a murder suspect in the CSI: Miami episode "Dangerous Son", Mark in Boogeyman 2, Paul Shapiro in Saving Grace, Ryan Stephenson in Bones, Jeff Ellis in Without a Trace, Seiji Amasawa in the English dub of Whisper of the Heart, and Kevin Mather in The Deep End episode "An Innocent Man". In March 2012, it was announced that Gallagher would be co-starring with Jake Weber in Scared of the Dark, directed by Takashi Shimizu. Since 2002, Gallagher has been the voice of Riku in the video game series Kingdom Hearts.
In April 2024, it was announced that Gallagher and his former co-stars, Beverley Mitchell and Mackenzie Rosman, would co-host the 7th Heaven rewatch podcast Catching up with the Camdens!.
