Posey was born in Baltimore, Maryland, the daughter of Lynda, a chef, and Chris Posey, who owned a Chevrolet dealership. She has a fraternal twin brother, Christopher. Posey's unisex first name was a tribute by her father to 1950s supermodel Suzy Parker. After Posey's birth, the family moved to Laurel, Mississippi where her mother worked as a chef and culinary instructor for the Viking Range Corporation Read more...

Posey attended the State University of New York at Purchase, where she roomed with actress Sherry Stringfield. Fellow actors in her SUNY Purchase acting company included Adam Trese, Reno Wilson, Todd Baker, and Josh Hartnett.

Posey's first break was in television, when she won the role of Tess Shelby on the daytime soap opera As the World Turns. (Stringfield, Posey's roommate, was also cast Read more...

Although Posey primarily works in film, she has appeared in several television projects.

Posey was previously considered for the roles of Rachel Green in Friends (which went to Jennifer Aniston), of Kimmy in My Best Friend's Wedding (which went to Cameron Diaz), and of Althea in The People vs. Larry Flynt (which went to Courtney Love).