In 2006, Holt won the role of Emma Gilbert in the Network Ten children's television series H2O: Just Add Water. The show has earned a Logie Award and Nickelodeon Australia Kids' Choice Award. While the series was renewed for a third series, Holt left the show after signing on for the sequel to the 2007 film The Messengers, titled Messengers 2: The Scarecrow. Filming took place in Sofia throughout 2008. Starring alongside Norman Reedus and Heather Stephens, the film was released 21 July 2009 straight-to-DVD.

In addition to television and film roles, Holt has appeared in advertisements for Dreamworld, Sizzlers and Queensland Lifesaving.