Williams was born in Christchurch, where she spent her childhood. At a very young age, she decided to become an actress: she then started performing in amateur theatre and attending acting courses. She moved to London, where, starting in 2001, she trained at Mme Course, Acting for Screen and the Globe Theatre, joining its theatre company.
In 2002 she participated in the Edinburgh Festival Fringe acting in Gogo the Boy with Magic Feet, for which she won a Total Theatre Award. After going back in New Zealand, she worked at the Court Theatre in Christchurch; she moved North in 2004 to graduate in Performing and Screen Arts at the New Zealand Drama School: she gain the degree in 2006. In 2007 she moved to Auckland, where she joined the Auckland Theatre Company, playing the lead role in Romeo & Juliet. Her television career began in 2005, acting in the movie Meet Me in Miami; then she appeared in television series Spartacus: Blood and Sand, its prequel Spartacus: Gods of the Arena and Legend of the Seeker. In 2008, Williams acted in a spot for Griffin Solay. Two years later, she won two NZ Herald Best of Theatre Awards. In 2011, she appeared in the video of the song Myth Reducer by Sleeping Dogs and she joined Shortland Street, playing Lana. In 2012, Williams portraited Aurelia in Spartacus: Vengeance again. She resigned from Shortland Street in early 2013.