Vanna White guest stars on "American Idol" with Ryan Seacrest for a contestant's performance.

Vanna White, best known for her role on "Wheel of Fortune," will make a special guest appearance on "American Idol" alongside host Ryan Seacrest. The appearance will take place on Monday's episode, where White will help Seacrest introduce a contestant's performance. White will join Seacrest as a co-host on "Wheel of Fortune" when he takes over for Pat Sajak in the future.