After starring opposite Steve Burton (who would go on to gain fame on General Hospital) in the school's production of Romeo and Juliet, she was signed by an agent.
She guest-starred in the 1992 Law & Order episode "Sisters Of Mercy" as a meth addict who accuses a nun of sexually abusing her.
Williams appeared as Dr. Natalie Durant on the NBC television show Medical Investigation which began in the fall of 2004 and ran for 20 episodes before being canceled.
In August 2008, Williams was cast in a lead role as psychologist Dr. Gillian Foster in the Fox series Lie to Me, opposite Tim Roth as Dr. Cal Lightman, which ran for three seasons and ended in 2011.
[5] In April 2011, she was cast in a guest role as Shelley Chamberlain, a grieving mother on a killing spree[6] in the CBS series Criminal Minds.
In October 2011, she was cast in a guest role as a kidnapped child's mother called Elizabeth Flint in the CBS series The Mentalist.
[7] On August 12, 2015, Ties That Bind, the first original series from the Up Network, debuted with Williams playing police detective Allison McLean.