Jack Osbourne Welcomes Daughter Pearl

Lisa Stelly and Jack Osbourne Credit: FameFlynet

Welcome to the world, Pearl Osbourne!

Jack Osbourne's fiancee, Lisa Stelly, welcomed the couple's first child -- a daughter -- his rep confirms to Us Weekly.

Little Pearl weighed a healthy 8 lbs., 6 oz. at birth.

The entire Osbourne family -- including Jack's mom, Sharon, and sister, Kelly -- have been anxiously awaiting Pearl's arrival, and tell Us Jack will be a terrific father.

"He's very nervous -- but nervous-excited," Sharon, 59, told Us Thursday. "He'll be a very good dad. I think he'll be very strict, but he'll be a very good dad."

Auntie Kelly can't wait to spoil her niece -- with the most comprehensive baby wardrobe in town!

"I already told him that this baby…is going to be the best-dressed baby there is," Kelly 26, has said. "'You're not buying the clothes -- I am!'"

The youngest child of Sharon and Ozzy Osbourne, Jack, 25, announced his engagement to aspiring actress Stelly in September and confirmed their pregnancy two weeks later.