Kimberly Stewart gave birth to a healthy baby girl weighing 8 lbs., 9 ozs., in Los Angeles on Sunday night.
This is the first child for the baby's father, Oscar-winner Benicio del Toro, 44, and the 31-year-old model, actress and daughter of singer Rod Stewart.
"Benicio is the father and very supportive," del Toro's rep said to Us Weekly.
Proud grandfather Rod, 66, and his wife Penny were at the hospital during the delivery, along with Kimberly's mother; Rod's first wife, Alana Collins.
Kimberly and Benicio announced earlier this year they were expecting a child, but were not a couple.