Jack Osbourne has become a father.

The son of Sharon and Ozzy Osbourne and his fiance Lisa Stelly welcomed daughter Pearl today.

The news was confirmed via Twitter of the arrival making Fashion Police star Kelly Osbourne an aunt.

"Jack and Lisa's happy baby news has been broken on Twitter tonight by HELLO! Magazine," editor Rosie Nixon wrote.

"The couple welcomed baby Pearl today, weighing 8lbs 6ozs."

The new parents had revealed they were expecting their first child less than two weeks after confirming their engagement last September. They had been dating for just four months.

The 26-year-old said that he was "excited and a little nervous" about becoming a dad.

Sharon also revealed that she was going to be the "grandmother from hell" because she was going to spoil the baby "so bad."

She told Ellen DeGeneres this week that the baby was late "like its Grandma" as she was due last week.