Kelly Lee Osbourne was born in London, England, on October 27, 1984. This girl is the daughter of heavy metal pioneer John "Ozzy" Osbourne and Sharon Osbourne, Ozzy's longtime manager and wife. Kelly has four siblings: Jessica Starshine and Louis Osbourne, born in 1972 and 1975, respectively, are from Ozzy's former marriage, while Aimee and Jack Osbourne, born in 1983 and 1986, are Kelly's full siblings.

To say that Osbourne had an unusual upbringing would be an understatement. Kelly was born during Ozzy's 1980s comeback heyday, and spent as much time in hotel rooms while her father was on tour, as she did in the English countryside being traditionally schooled. As a result, Kelly and the rest of the Osbournes became unusually combative and frank, but close, too.

In 1995, the Osbournes made a permanent relocation to Los Angeles, a strategic move from which Ozzy was to make his next comeback. But home life continued to be dysfunctional, and Osbourne dropped out of school by the tenth grade.