The 41-year-old actress, who already has a son Milo with David, is elated with the news, reported E!Online.
"I'm in my Mistresses dressing room and I wanted to share with you guys that I am expecting a little, sweet baby girl. David, Milo and I could not be happier. Truly, we could not be happier. So exciting!," Milano said.
She announced her second pregnancy in March.