Michael Sheen, 50, and his 25-year-old girlfriend, Swedish actress Anna Lundberg, welcomed their first child on September 23.
Today saw the actor share a photo to his Twitter page of him carrying the bundled-up tot in a car seat, revealing they had named her Lyra.
He also reached out to thank midwifery staff at Singleton and Neath Port Talbot hospitals in a heart-felt message.
"Happy to say that at 8:41 am on Monday September 23rd our beautiful daughter Lyra was born," Sheen shared. "Thank you so much to Louise & all the brilliant midwives at both the Singleton and NeathPortTalbot hospitals."
Happy to say that at 8:41 am on Monday September 23rd our beautiful daughter Lyra was born. Thank you so much to Louise & all the brilliant midwives at both the Singleton and NeathPortTalbot hospitals. ❤️👶🏴🇸🇪😍 pic.twitter.com/Y4Xdt7GkMz— michael sheen (@michaelsheen) September 30, 2019
Sheen later went on to congratulate well-wishers for their congratulations in the wake of the big announcement.
He wrote in another message to the micro-blogging site: "On behalf of Anna and myself thanks to everyone for your lovely messages of congratulations. It’s been a wonderful, bleary-eyed week full of love and kindness and extraordinary poo. #NotReferringToMyself."
While Lyra is Lundberg's first child, the Twilight actor is already father to a 20-year-old daughter, Lily Mo, whom he shares with actress and former girlfriend Kate Beckinsale.
Sheen announced back in July that he was to be a father again, referencing his Good Omens role as he wrote on Twitter: "Very happy to let everyone know that my partner Anna and I are expecting a little angel of our own. (Just to be clear - we’re having a baby!)#nottheantichrist."