Harris, who is also an E! News correspondent, and her husband, financial wholesaler Michael Hess, welcomed their first child -- Josselyn Sydney Hess -- at 1:49 a.m. Sunday in Los Angeles.
"Michael and I are ecstatic to have a little girl to welcome into our lives," Harris told E! Online. "We can't wait to introduce her to our family and friends."
ABC told People magazine it isn't going to announce who will replace Harris on "Dancing with the Stars" so viewers will have to tune in for the program's premiere to find out.
Notable deaths of 2014 [PHOTOS]
Polly Bergen, Emmy Award-winning actress, dies