Ozzie Osbourne is officially a grandpa!

Jack Osbourne and fiancee Lisa Stelly has just welcomed their first child, a daughter named Pearl, his rep confirms to Us Weekly.

The little girl weighed in at a healthy 8 lbs., 6 oz. and the entire Osbourne family -- including mom Sharon and sis Kelly -- were at the hospital during the birth of the family's first grandbaby!

"He's very nervous -- but nervous-excited. He'll be a very good dad. I think he'll be very strict, but he'll be a very good dad," proud grandma Sharon told US, on Thursday.

Proud Auntie Kelly also exclaimed: "I already told him that this baby…is going to be the best-dressed baby there is. You're not buying the clothes -- I am!'"

Congrats to the Osbourne fam!