Crew was born in Langley, British Columbia. Her mother is a legal secretary and her father is a telecom worker. Crew attended Brookswood Secondary School in Langley, BC. She began her acting career when she was cast in the musical Dragon Tales during her fourth grade in elementary school. Three agents contacted her, and she has been acting ever since. She did a Coca-Cola commercial and acted in stage plays like Stalling, Cordstons Courts, and Langley, the Musical. Crew attended the American Academy of Dramatic Arts.

Crew got her big break at age 18 for playing Tanis McTaggart on the YTV teen dramedy series 15/Love. After leaving the show in 2005, she guest starred on the television series Life As We Know It and Smallville. From 2006 to 2008, she played Carrie Miller on the CTV drama series Whistler, for which she won Best Lead Performance by a Female in a Dramatic Series at the Vancouver-based Leo Awards.

Crew got her Hollywood break when she landed a role in the 2006 horror film Final Destination 3, which went on to international success, grossing $19,173,094 in its opening weekend and eventually grossing $112,798,051 worldwide. She then continued to star in several successful Hollywood productions including She's the Man and Sex Drive. In 2009, Crew starred in the horror film The Haunting in Connecticut. The film opened at #2 at the box office and ultimately grossed $55,325,526 in the United States and Canada alone, making her highest grossing picture to date and went on to make $72,742,856 worldwide. In 2009, Crew was cast alongside Zac Efron and Kim Basinger in Charlie St. Cloud, which was released on July 30, 2010. She is also set to star in Breaking the Girl and Repeaters.