Bell and her husband, Adam Beason, are already the parents of a 7-year-old daughter, Gemma.
Their son was born Saturday morning, and weighed in at 7 pounds, 7 ounces, Bell's publicist told People.com exclusively.
The actress is best known for her work on TV's "JAG" and "Army Wives."
Beason is a film and TV production assistant and occasional actor.
NASA celebrates Earth Day with #GlobalSelfie
Lytro unveils camera that can focus a photo after shooting it