Other celebrities announced Wednesday include Denzel Washington, Renee Zellweger, Kathy Bates and Richard Branson. Kareem Abdul-Jabbar, Lance Armstrong and Elizabeth Edwards were previously announced as participants.
There will be musical performances from Stevie Wonder, Neil Diamond, The Edge, Herbie Hancock, Lady Antebellum and Leona Lewis, Queen Latifah, Martina McBride and Billie Joe Armstrong of Green Day.
The telecast airs September 10 in 195 countries. "Stand Up to Cancer" is aimed at raising money to speed up innovative cancer research.
Telethon viewers will be asked to pledge donations by phone or on the "Stand Up to Cancer" website.
The Associated Press contributed to this report.