She has a younger half-sister named Madison Grace Reed.She and her family relocated to Hollywood, California in 2003.
She rose to fame on Nickelodeon in the 2000s, starring as Lola Martinez on Zoey 101 (2005–2008) and later Tori Vega on Victorious (2010–2013). Justice has also appeared in the films The Boy Who Cried Werewolf (2010), Fun Size (2012), The First Time (2012) and Naomi and Ely’s No Kiss List (2015).In 2015, she starred in the lead role as Lindy Sampson on the MTV television series Eye Candy. In music, Justice has recorded several songs for the soundtracks of her acting projects, including Victorious and the Nickelodeon musical Spectacular!.
On October 20, 2016, Justice played Janet Weiss, one of the lead roles in The Rocky Horror Picture Show: Let’s Do the Time Warp Again. Starring an ensemble cast led by Laverne Cox, the film premiered on the Fox network. It is a tribute to the cult classic 1975 film of the same name and directed by Kenny Ortega, using the original script written by Richard O’Brien and Jim Sharman.