Bianca was born in Seattle, Washington, the daughter of Patti (ne Campana) and Dr. Aurel Jan "Relo" Kajlich. Her father was Slovak and her mother is of Italian descent.

She is a graduate of Bishop Blanchet High School in Seattle, Washington, and attended Washington State University in Pullman, Washington.

She began her career with the Olympic Ballet Theater as a ballet dancer in Edmonds, Washington. After spending seven years with them she decided on acting. By that time she had already performed lead roles in The River, Swan Lake, and The Nutcracker.

Her first acting part was in an advert for Kragen Auto Parts. Kajlich has since appeared in the films Bring It On, 10 Things I Hate About You, Halloween: Resurrection and, memorably topless, as a scheming lap-dancer in 30 Minutes Or Less (2011).

She has also had recurring roles in the television series Boston Public, as Lisa Grier, and Dawson's Creek, as Natasha Kelly. She also had roles in two canceled television series, UPN's Rock Me Baby and the Fox drama Vanished. Bianca appeared on an episode of the USA Network's Psych entitled "Psy vs. Psy" as a psychic FBI agent who ends up not being who she appears to be.

She appeared as a major character in an episode of Fox's short-lived action TV show, Fastlane, as a prostitute named Bree whose pimp wants her dead. She had a quick appearance as a punk nose piercing girl on the TV series Freaks and Geeks, and she played Jennifer on the CBS comedy Rules of Engagement.

She was ranked No. 74 on the Maxim "Hot 100 Women of 2004" and No. 63 on the Maxim "Hot 100 Women of 2007