Liberato was born in Galveston, Texas, the daughter of Rhondelle, a former real estate agent, and George Liberato. Her first significant role came in "Galveston: The Musical" when she was seven. In the summer of 2005, she attended a week-long acting camp in California, where she attracted the attention of Central Artists. Charmed by Liberato's "great charisma and a very natural delivery," the agent asked Liana to travel to Hollywood.
In 2005, Liberato made her acting debut in the television series Cold Case. Liberato has continued to guest appear on television shows Sons of Anarchy, CSI: Miami and House MD. Liberato appeared in the music video for 7 Things by Miley Cyrus. In 2007 Liberato portrayed the role of the protagonist in the 20th Century Fox adventure film The Last Sin Eater. The film centers on a 10-year-old girl who discovers a secret sin haunting her community. That same year she starred in the straight-to-DVD romantic drama film Safe Harbour.