Her breakthrough role as Grace Heke in the Lee Tamahori film, Once Were Warriors, based on the book of the same name by Alan Duff, was as a "sixteen-year-old newcomer [when Kerr-Bell] was discovered by casting director Don Selwyn while accompanying a friend to the auditions for Once Were Warriors. She had never acted before but when Selwyn asked her if she'd like to read, she accepted and instantly won over Rena Owen and Temuera Morrison, who play her character's parents. About her role she says, "Some things I had to pretend but other things I could relate to quite well. I know a lot of people whose father would beat them and their mother and I could relate to Grace helping her mother bring up the kids because I have a little brother and two baby sisters. Director Tamahori says she "was just a natural. I was astounded by what she had behind her eyes and the sheer timeless beauty of her face. She looked both old and young and I had seen faces like that in a lot of research I'd done. She seemed to carry a lot of history with her and it was a haunting face". In 2014 she recalled her 1994 role for a documentary made on the film's 20th anniversary.