Carpani grew up on a property near Dural, in Sydney's Hills district. She studied acting at the Australian College of Entertainment at Macquarie University and at the Drama Works Drama Company. She is most famous for her role as Jodi Fountain McLeod on the Australian TV drama McLeod's Daughters. Carpani also had a role in the film Hating Alison Ashley, starring Delta Goodrem, and appeared in All Saints.

Carpani left McLeod's Daughters to pursue her career in the United States. She had been cast in the new CBS pilot, Law Dogs with Janeane Garofalo, but the series was not picked up. She appeared in 7 episodes of season one of Cane. Rachael then returned to McLeod's Daughters as Jodi Fountain McLeod for the final episode on 31 January 2009.

Carpani is currently one of the faces for the Telstra Next G network.

She appeared in episode six of NCIS: Los Angeles in November 2009, playing a small role alongside Chris O'Donnell and LL Cool J.

At present, she is dating Matt Passmore, who is currently starring in A&E's The Glades as Jim Longworth.

Carpani used to be in a relationship with Australian Rules Football player Chad Cornes.