The 60-year-old "Saturday Night Live" star announced the arrival of the new born on Instagram, and captioned the pic: "Here we go again!"
His wife Hilaria, 34, shared the same photo to social media and wrote: "He's here! He's perfect! 8lbs 2oz".
The new addition joins siblings Leonardo Angel Charles, 20 months, Rafael Thomas, two-and-a-half, and Carmen Gabriela, four-and-a-half. Balwin is also dad to 22-year-old daughter Ireland Baldwin, from his previous marriage to actress Kim Basinger.
The couple, who tied the knot in 2012, announced they are expecting their fourth child last November with an adorable Instagram picture that had them playing on the floor with their kids.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)