The Clueless star was promoting her new book The Kind Diet: A Simple Guide to Feeling Great, Losing Weight and Saving the Planet on The Late Late Show with Craig Ferguson when a loud bang sounded and the lights cut out.
But Silverstone simply laughed off the mishap as presenter Ferguson joked about the situation with the audience, and they finished filming with a flash light.
The black out, which struck Los Angeles on Tuesday afternoon, has been blamed on high winds which swept across the city, causing numerous power failures throughout the day.