Sergeant was born in 1980 in Malaysia and raised in Brisbane, Australia. While in high school, she had dreams of being a marine biologist, but a hobby for drama acting prompted her to audition and receive acceptance at the National Institute of Dramatic Art. She graduated in 2000 at twenty years old. Despite landing television roles and even producing a play fresh out of drama school, Peta decided to abandon the industry and travel overseas for eighteen months, which helped her gain a commitment to acting. Her notable television credits include British science-fiction and drama series Jeopardy, Headland, and numerous Australian drama series such as Last Man Standing, All Saints, Canal Road and Satisfaction. She starred in the films Iron Sky and Crawlspace.
- She ships Klayley.
- Despite popular belief, she actually doesn't have a Twitter account.
- She has been married to Rohan Nichol since 2008.
- She graduated with a Performing Arts degree in 2000 from Australia's National Institute of Dramatic Art (NIDA).