Kernohan began her career in 1988 when she appeared in the low-budget slasher film Fatal Pulse. She appeared in several other films during 1988 including Roger Corman remake Not of This Earth, the post apocalyptic action film She-Wolves of the Wasteland and the film in which she is best known for, Critters 2: The Main Course, where she plays "Lee", the bounty hunter. The same year she appeared in the documentary The Decline of the Western Civilization Part II: The Metal Years. In 1989, she appeared in the action film Tango & Cash and the Playboy documentary Playboy: Sexy Lingerie. In 1990 she starred in Angel III: The Final Chapter, and her final film came in 1991 when she played herself in the direct-to-video film Scream Queen Hot Tub Party.

In 1993, Kernohan died in hospital of injuries following a car accident.