Jack Osbourne and his fiance Lisa Stelly have welcomed their first child, a daughter named Pearl.
The baby was born on Tuesday, April 24. The son of heavy metal rocker Ozzy Osbourne confirmed the news on his Twitter page, reTweeting a report by Hello! magazine that said his new baby weighed 8 pounds and 6 ounches.
His sister, Kelly Osbourne, Tweeted her excitement, saying "I am one proud Auntie!"
The Osbourne family matriarch and "The Talk" co-host Sharon Osbourne also took to Twitter to express her delight.
"Today I witnessed my first grandchild being born, life changing experience," she Tweeted. "She is an angel."
Jack Osbourne, 26, revealed that he and Stelly were expecting a child in an interview on the CNN show "Piers Morgan Tonight" on Oct. 11, 2012, about two weeks after Stelly, 26, announced on her Twitter page that the two were engaged.
"I'm about to be a father," Jack Osbourne said on the program, as he sat beside his parents. "I'm excited. I'm a little nervous, but I'm excited. It's going to be fun. I'm not going to do a reality show though."
"I'm in shock," Ozzy Osbourne said. "I think it's fabulous."
Jack Osbourne and his family starred in the MTV reality series "The Osbournes," which ran between 2002 and 2005 and depicted the family's wacky home life, as well as frequent squabbles between the Osbourne siblings.
Ozzy and Sharon Osbourne are also parents to a 29-year-old daughter, Aimee, who did not appear on the show.
Jack Osbourne's new bundle of joy is the first grandchild for Sharon Osbourne. Her husband and his first wife, Thelma Riley, have a daughter and son together and they have two children each.
"I'm happy because it's what Jack wants," Sharon Osbourne said on "Piers Morgan Tonight." "I've always wanted to be a grandma."