At the age of seventeen, Barrett started modeling through Europe. In 1995 she landed her first television break as a cast member on MTV's Real World season in London. This made her perhaps one of the very few people to crossover from reality television to mainstream success in the film industry. After the show, she attended the British Academy of Dramatic Art in Oxford, England. Her first film role came in 1997 in Campfire Tales. Since then, she has been in numerous movies and television shows.

On December 29th, 2004 she married actor Gabriel Macht.