The new dad can be seen cuddling up to his tiny baby in a photo taken on November 2.
"It is boy. His name is Valor and he was six pounds and two ounces," said a source close to the new family. "He is a beautiful, healthy baby boy. Everyone is so excited and happy."
Hirsch made the trip to Florida, where the boy was born, and is spending some time bonding with his new son. The boy's mother is reportedly "a nice, down to earth girl and she will make a great mom."
Hirsch reportedly met the mother of his child at an Oscar after party early this year, and the pair had a short fling. The two remain friendly and will share parenting responsibilities.
The actor has yet to publicly comment on his new bundle of joy.