His girlfriend Sonni Pacheco gave birth to their daughter Ava Berlin Renner.
"They are beyond thrilled," the "Hurt Locker" and "The Avengers" star's representative told People.com in a statement. "Mother and daughter are doing great."
No other details about the birth were immediately available.
Rumors stating Renner was to become a father had been circulating for months, but he did not address them until after the child was born.