37-year-old Danny, who played Steven Hyde in the hit sitcom, shared their exciting baby news via Instagram on Wednesday night (19 February), alongside an adorable photo of him cradling his little girl.
"Hello friends. Beyond thrilled to announce the birth of our daughter Fianna Francis Masterson!" he wrote. "Mum and baby are doing amazing."
He also joked: "You can all refer to me as DJ Dadpants from now on..."
Bijou added a cute picture on her own account, writing: "Fianna Francis Masterson, 2/14/14 8LBS, 5OZ, 21in, she is a perfect valentine!!! (sic).
Danny and Bijou, who appeared in Almost Famous, married in an Ireland in October 2011 after eight years of dating.
Danny currently appears in the comedy series Men At Work, which is now in its third season.
More stars who have welcomed babies in 2014 below!
Copyright: Rex Features WENN/Matthew Taylor/Daniel Deme/Josiah True/Matthre Taylor/Joe
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