She has starred in the films The Baby-Sitters Club (1995), She's All That (1999), and Josie and the Pussycats (2001), and in the television series Into the West and Perception.

In 1997, Cook appeared in a leading role in the film Country Justice as a 15-year-old rape victim who is impregnated by her rapist.

She took the lead role in 2001's Josie and the Pussycats, which turned out to be a box office failure, although it has since become a cult classic.

She also appeared as a main cast member in the 2005 television miniseries Into the West produced by Steven Spielberg.

She has appeared in numerous episodes of the Seth Green comedies Titan Maximum and Robot Chicken.

In February 2010, Cook signed on to play the female lead role in Fox TV's comedy pilot Nirvana.

[6] She had a role in the Western horror film Vampire, the English-language feature debut of Japanese director Iwai Shunji.

[7] In 2012, Cook signed on to play the female lead role in the TNT crime drama series Perception opposite Eric McCormack.

In 2020 Cook appeared in the fifteenth season of Criminal Minds playing the role of Max in the final episodes of the series.

[15] Cook first gained national attention in 1997, when she was featured in an updated This Is Your Brain on Drugs public service announcement (PSA) television advertisement, in which she proceeds to destroy a kitchen with a frying pan.