Nigel Lythgoe, who is the producer of Fox's "So You Think You Can Dance," confirms the 30-year-old actress will perform for the reality contest's 100th episode, airing July 23.
Holmes will pay homage to Judy Garland. In a taped number, she'll sing and dance to the Garland classic "Get Happy."
Holmes' TV cameo is meant to promote the new foundation she launched with Lythgoe and "Dancing With the Stars" judge Carrie Ann Inaba.
The nonprofit, called Dizzy Feet, aims to support dance education and programs, and talented dancers who can't afford training.
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