Her publicist says in a brief news release Tuesday that Sadie Grace LeNoble was born Jan. 27 in Los Angeles, and mother and daughter are doing great. There are no other details.
People.com was first to report the birth.
The 39-year-old "Married . With Children" and "Samantha Who?" star and 41-year-old Dutch musician Martyn LeNoble became engaged last Valentine's Day. Her pregnancy was announced in July.
Applegate had a double mastectomy in July 2008 and reconstructive surgery months later. She is now cancer-free.