Born in Brisbane, Queensland, the daughter of a firefighter, Barrett entered and won the annual Dolly Covergirl contest in Australia in 1988, while attending Kenmore State High School, and started modeling at the age of seventeen through Europe. In 1995, she had her first television appearance as a cast member on MTV's The Real World: London; she later attended the British American Drama Academy in Oxford. Her first film role came in 1997 when she starred in Campfire Tales.

Barrett appeared in the September 1998 issue of Maxim magazine in an article promoting the new fall television series. Her appearance served to promote her appearance in the NBC primetime soap opera Wind on Water but the show did not last past the first season.

Barrett was previously engaged to American actor Chris Hardwick, host of MTV's Singled Out. On 29 December 2004, she married American actor Gabriel Macht. The couple had their first child, a girl named Satine Anais Geraldine Macht, on 20 August 2007 in Los Angeles.

Barrett enjoys skydiving, explaining 'it gets scarier the more you do it. After a while you realize you're flinging yourself out of a perfectly good plane for no apparent reason'.

On 28 August 2009, Barrett was naturalized as a U.S. citizen at the Los Angeles Convention Center.[verification needed]