Vassey played teenager Emily Ann Sago on the soap operaAll My Children from 1988 to 1991. From 2004 to 2005, she had a recurring role on the series Tru Calling as Dr. Carrie Allen.
She appeared in several episodes of the sitcom Two and a Half Men. In the episode "The Last Thing You Want is to Wind Up with a Hump" in 2003, in "Twanging Your Magic Clanger" and "The Crazy Bitch Gazette" (2011),[4] and in "Nice to Meet You, Walden Schmidt" (the season premiere with Ashton Kutcher).
From 2005 to 2010, Vassey had a recurring role as Wendy Simms on CSI: Crime Scene Investigation. Starting with the tenth season, Vassey was promoted to a regular cast member and began appearing in the show's opening credits. Entertainment Weekly reported on June 1, 2010 that Vassey would not be returning for the show's eleventh season. She guested in one episode of that season.
Vassey is married to David Emmerichs, a camera operator.
In 2002, along with fellow actress Kristin Bauer, Vassey started a company called Neurosis to a T(ee), which designs and sells slogan-covered T-shirts for women. The slogans poke fun at female worries and neuroses, often relating to relationships.[6]