Jack Osbourne and his fiancée Lisa Stelly welcomed baby daughter Pearl into the world on Tuesday. Sharon took to her Twitter page to gush about the family's new arrival.
"Today I witnessed my first grandchild being born, life changing experience. She is an angel (sic)," she wrote on her personal page.
Jack and Lisa's baby girl weighed in at 8lbs. 6oz.
Jack's sister Kelly also tweeted her delight at the Osbournes' new addition.
Sharon has previously revealed she can't wait to shower her grandchild with gifts.
"I'm going to be the absolute nightmare grandmother that is going to do everything wrong. I'm just going to spoil, spoil, and that's the job of a grandparent," she said.
Sharon - who wants Pearl to call her "Shazza" - joked it was an Osbourne family trait to be late, when the baby's due date was pushed back.
The whole family are over the moon about the recent Osbourne addition.