The 41-year-old actor's wife, Jessica, gave birth to a baby boy in New York on Friday (29.06.12) and the couple have named their son Noah Rev Maurer.
The tot weighed in at a healthy 9lbs 4oz and both mother and baby are doing well.
Josh and Jessica got married in March and just days later announced they were expecting their first child together.
He said: ''I've heard that one of the things that does happen being a parent is that you are emotional in ways that are surprising and that feelings happen inside of you that you have never understood or known - and I must say already the experience of being pregnant, that's been true. We're still a few months away but everyone always says that you never know what it is until you experience it and so far that's absolutely true.''