Vernon was briefly (4 episodes) a regular on Who's the Boss? in 1990 as a girlfriend of Tony Micelli (Tony Danza). She appeared in four episodes of L.A. Law in 1994 as A.D.A. Belinda Fox and seven episodes of Nash Bridges as Whitney Thomas. In 1993 she starred in an episode of Tales from the Crypt entitled "Till Death Do We Part" with John Stamos.
Vernon is known for her recurring role as Ellen Tigh on Battlestar Galactica. In April 2009, she made a guest appearance on CSI: Crime Scene Investigation entitled "A Space Oddity" which also featured cameos by her former Galactica producer Ronald D. Moore and co-stars Grace Park and Rekha Sharma. She appeared in one episode of Star Trek: Voyager as a member of Species 8472 impersonating a human in the episode "In the Flesh". She also guest stars in two episodes of Heroes ("Close to You" and "Pass/Fail") as Vanessa Wheeler.