The 38-year-old Chen told viewers Tuesday that her due date is Oct. 4.
Chen, who also hosts "Big Brother," says she won't be taking maternity leave from the CBS reality show.
Moonves is CEO of CBS. The couple were married in 2004. He has three children from a previous marriage.
Related Content from AccessHollywood.com:
VIEW THE PHOTOS: The Pregnant Ladies Of Primetime
PLAY IT NOW: Celebs Attend An 'Irie' Charity Event
PLAY IT NOW: Access Exclusive: Christian Siriano's Fierce Mama Fashion