Fox appeared in seasons 2 to 3, until the show was cancelled by ABC in May 2006.
She began her acting career in 2001, with several minor television and film roles, and played a regular role on the Hope & Faith television sitcom.
In 2004, she made her film debut with a role in the teen comedy Confessions of a Teenage Drama Queen.
In 2007, she co-starred as Mikaela Banes, the love interest of Shia La Beouf's character, in the blockbuster action film Transformers, which became her breakout role.
Fox reprised her role in the 2009 sequel, Transformers: Revenge of the Fallen.
Later in 2009, she starred as the eponymous lead in the black comedy horror film Jennifer's Body.
Fox is also considered one of the modern female sex symbols and has appeared in magazines such as Maxim, Rolling Stone and FHM. Fox has spoken extensively of her time in education; that in middle school she was bullied; consequently she ate lunch in the bathroom to avoid being "pelted with ketchup packets".She attended a dance class at the community center there and was involved in Kingston Elementary School's chorus and the Kingston Clippers swim team. She said that the problem was not her looks, but that she had "always gotten along better with boys" and that "rubbed some people the wrong way".Fox also said of high school that she was never popular and that "everyone hated me, and I was a total outcast, my friends were always guys, I have a very aggressive personality, and girls didn’t like me for that. In the same interview, she mentions that she hated school and has never been "a big believer in formal education" and that "the education I was getting seemed irrelevant. At 15, Fox made her acting debut in the 2001 film Holiday in the Sun, as spoiled heiress Brianna Wallace and rival of Alex Stewart (Ashley Olsen), which was released direct-to-DVD on November 20, 2001.In the next several years she guest-starred on What I Like About You and Two and a Half Men, as well as being an uncredited extra in Bad Boys II (2003).In 2004, she made her film debut in Confessions of a Teenage Drama Queen co-starring opposite Lindsay Lohan, playing the supporting role of Carla Santini, a rival of Lola (Lohan).Fox was also cast in a regular role on the ABC sitcom Hope & Faith, in which she portrayed Sydney Shanowski, replacing Nicole Paggi.