Osbourne was born in Westminster, London. She has an elder sister, Aimee, and a younger brother, Jack. She has two half-siblings: Jessica Hobbs and Louis John Osbourne from Ozzy's first marriage. She had an unofficially "adopted" brother, Robert Marcato, whom Sharon and Ozzy took in after Marcato's mother died. Kelly grew up travelling with her father as he went on tour, and lived in more than 20 homes between the UK and the USA.
Osbourne and the rest of her immediate family (without Aimee) were thrust into the international spotlight with the MTV reality show The Osbournes, which aired from 2002 to 2005. The series chronicled their day-to-day life, and the show became a hit for its portrayal of a dysfunctional, though close-knit family in which metal music, profanity and other harshness were a daily part of life. Kelly, the middle child, emerged (according to Rolling Stone) as "a wickedly funny, brutally honest, pint-size, potty-mouthed spitfire." The series started when she was around the age of sixteen, ending around the ages of eighteen or nineteen. Kelly said in an interview for The Osbournes DVD that the crew were only actually supposed to be there for a few weeks but ended up staying for a few months and that the constant cameras focusing on her and her family was stressful.
Both she and the Osbournes family have been parodied in Channel 4 comedy, Bo' Selecta. In which the rubber-masked Kelly, played by Leigh Francis, has her own show and is always being censored for swearing with bleeps.
In March 2009, Osbourne returned to television with the rest of the Osbourne family on Osbournes: Reloaded.
Her debut album, Shut Up, was released in 2002 to moderate American sales, but good European sales, which was debuted with Houston rock band Pure Rubbish at the 2002 MTV Movie Awards. Osbourne's 2002 debut with Epic Records, "Shut Up!", debuted at #1 on Billboard's Heatseekers chart. The album was met with mixed critical reviews and, by May 2003, Osbourne was dropped from Epic Records. By autumn she was on the Sanctuary label, later recording a duet of "Changes" (a Black Sabbath song) with her father. The duet hit #1 on the UK charts. "Changes" was one of a few tracks to have fallen down the charts (From 1 - 3) whilst selling more copies than the week it reached number 1. Osbourne was the first artist to top all three of the Billboard charts dance surveys in the same week with the "Chris Cox Club Remix" of "One Word". The album "Sleeping In The Nothing" was not without controversy, due to its reportedly heavily-altered album cover, in which Osbourne appeared slimmer, despite her previous assertions of being happy with her size.
During an interview in late 2005, Osbourne denied reports she was ending her music career, saying: "I don't know where the quit rumours came from - I've just recorded a version of "Girls Just Want to Have Fun" with Cyndi Lauper".
Osbourne was forced to back out of her final performance in West End musical Chicago after the 31 October 2007 incident that injured her back. She later went on to win theatre actress of the year at the glamour awards in the UK. On the same night, she attended the Sony Radio Academy Awards, where she was nominated for the Rising Star Award, which she did not win.
Osbourne made her debut as an actress with a starring role on 7 October 2004 on the ABC high school teen drama Life As We Know It, where she played the supporting role of Deborah Beatrice Tynan. In June 2006, Osbourne played the role of Wendy from Peter Pan in The Queen's Handbag. In 2006, Osbourne provided a voice for the animated film Live Freaky Die Freaky. In July 2007, it was announced Osbourne was to take on the role of prison matron Mama Morton in the musical drama Chicago. Her seven-week run (from 10 September) in the musical at the Cambridge Theatre would be her stage debut, London's The Stage performing arts weekly reported.
In 2008 she features in the short musical film The Town that Boars Me by photographer Ben Charles Edwards. The film also features Sadie Frost, Jodie Harsh, Sophie Ellis-Bextor and Zandra Rhodes amongst others. The film is set to debut in late summer at the Portobello Film Festival. Osbourne will be starring alongside David Chokachi and Brooke Hogan in horror film Devour, set for US release in 2010. The film is currently in post production. In 2009 she appeared in an episode of Hotel Babylon, a British TV show aired on BBC One. She played Jo, a character very similar to herself. In August 2010, Osbourne began filming on new comedy "Should Have Been Romeo," Her first major role in Hollywood, She plays "Nicole" a funloving groupie. The film is due for release in the U.S on 7 April 2011. In December 2010 it was confirmed that Osbourne would be starring alongside Disney Star Miley Cyrus in So Undercover, she plays the sorority sister to undercover Private eye Miley Cyrus, The movie began filming in December 2010 and is set for a 2011 release.
Since her rise to fame, Osbourne has been called on to present for various events. Osbourne co-hosted the 2006 edition of I'm a Celebrity... Get Me out of Here! Now, a spin-off show of the main ITV1 programme. She hosted alongside Jeff Brazier in Australia, and Mark Durden-Smith in the London studio. Her one-off gigs include the 2002 MTV Movie Awards, Top of the Pops Saturday, MTV's Isle of MTV, MTV UK and Ireland's red carpet coverage of the 2003 MTV Europe Music Awards, Popworld, The Sunday Night Project, the 2005 MTV Australia Video Music Awards and Zane Lowe's BBC Radio 1 show. In spring 2006, Osbourne was one of the judges on Making Your Mind Up.
Osbourne presented ITV2's coverage of the National Television Awards with her brother Jack, and a documentary on Japanese pop culture called Kelly Osbourne: Turning Japanese for the same channel.
In January 2007, Osbourne began presenting Project Catwalk for Sky1. In Autumn 2007, Osbourne signed to BBC Radio 1 to host the Sunday night show, Radio 1's The Surgery, and on 7 October 2007 she went on air for the first time with the issue of self harm. She was scheduled to return to the show in early 2009 and whilst she was away, Aled Haydn Jones from The Chris Moyles Show presented the show. Aled has now been confirmed as a full time presenter. In spring 2008, she began contributing a teenage advice column to the tabloid newspaper The Sun, "Kelly Confidential", where she is billed as "the teen trouble shooter".
She appeared in Dancing with the Stars as a contestant, from September to November 2009. She and partner Louis Van Amstel took third place. The judges said Kelly was the contestant who grew the most and surprised them most, and they would be sorry to see her go.
Osbourne has presented on The Surgery with Kelly Osbourne on BBC Radio 1.
In August 2010, it was confirmed that Osbourne was signed up to appear alongside Joan Rivers as a fellow judge on Weekly Fashion show Fashion Police, Osbourne said "Its' a dream come true... and I can't fucking wait to work with Joan Rivers every week", she will offer up style comments following major red carpet events alongside Rivers, stylist George Kotsiopoulos and Guliana Rancic on U.S. cable network E!
In 2011, Osbourne filled in for her mother Sharon on U.S Daytime talkshow "The Talk" alongside Holly Robinson Peete, Leah Remini and Julie Chen, she was called upon to fill Sharons place on the show whilst auditions for "America's Got Talent" were held.
After her appearance on the reality show, Osbourne quickly began to be noted for her varied and trendy style among fashion commentators like Steven Cojocaru In 2004, Osbourne launched her own fashion line, Stiletto Killers, with her friend and former sponsor, Ali Barone. Stiletto Killers was a rock-inspired line of tees, knickers, hoodies, and sweatpants designed by Osbourne and Barone, emblazoned with cartoonish designs and punk rock phrases. There was also a more sophisticated couture branch, The SK Collection. Stiletto Killers closed in April 2006.
In 2006, Osbourne became the face of the high street chain Accessorize in a campaign which was seen across Europe, Canada, Russia, Australia, Brazil, South Africa and the Middle East. In the spring of that year, Osbourne modeled for Heatherette in a catwalk show which also featured Naomi Campbell. In 2010, she modelled a Chris Benz dress for Naomi Campbell's Fashion For Relief runway show for The White Ribbon Alliance to raise funds for mothers in Haiti.
In January 2011 it was confirmed that Osbourne would replace Taylor Momsen as the face of Madonna and daughter Lourdes' fashion range Material Girl. The brand is primarily aimed at teenagers, and is sold exclusively at Macy's store in the United States, and the Bay in Canada.
In 2011 Osbourne has become a regular Fashion correspondent for the E Channel, as part of her continued role on "Fashion Police" alongside Joan Rivers, she has been reporting live for the channel from events including the Oscars and the Grammys.