The 37-year-old actor's girlfriend, British actress Tamsin Egerton, gave birth to their first child, Hartnett's rep confirms to ET. The new dad was spotted outside St. Mary's Hospital in London, carrying his newborn.
The Black Hawk Down star met Egerton, 27, on the set of their film The Lovers in 2011, and they began dating in 2012, according to reports. Though the notoriously private actor has stayed mum on his big baby news, in April, Hartnett clearly had babies on the brain when he spoke to Playboy.
"I've had the viewpoint, 'You don't need money to survive. We can all just help each other out,'" he said, when discussing turning down plum roles in Hollywood, such as Batman in Christopher Nolan's hugely successful films. " ... I thought there was something to that notion, though, especially for actors and creative people. If we could just help one another and express ourselves, we'd all be happy. But then I think, 'Oh s**t, there are bills to be paid, and I’d have to get a car that’s safe for my kid.' I don't have a kid yet, but that's the idea coming into my head these days."