The Beverly Hills, 90210 star and husband Dean McDermott welcomed son Finn Davey McDermott on Thursday (August 30), according to E!.
Spelling announced the good news via her Twitter account, where she wrote: "It's a boy!"
On her website, she posted a photo of the newborn's hand grasping her finger.
Finn was born at 5.39pm, weighing 6lb 6oz and measuring 20 inches.
This is Spelling and McDermott's fourth child. The couple are already parents to Liam, 5, Stella, 4, and Hattie, 10 months.
Spelling recently defended wearing a bikini while pregnant, saying she was "proud" of her baby bump.