Lady Sovereign was born Louise Amanda Harman in 1985 to Colin Adien Harman and Nicola Parsons, an American, in the northwest London neighborhood of Wembley. She grew up in the run-down Chalkhill Estate — a council estate that has since been demolished — with her parents and two siblings, older sister Chloe Christie (born 1984) and younger brother Richie Colin (born 1987). Louise's parents were punk-rock fans, so she was exposed to a wide array of urban music, including punk, ska, garage rock, jungle, big beat, and R&B. When Louise's parents separated in 1997, she went to live with her father and siblings in nearby Neasden.[citation needed]

Louise was a tomboy who played football and hated wearing dresses. She had difficulty fitting in at school and was kicked out of Preston Manor High School at 15 because of her abysmal attendance record and poor behavior. A number of menial jobs followed, until Louise decided to pursue rap after hearing Ms. Dynamite on the radio: "When I heard Ms. Dynamite's track 'Boooo!' in 2001 it inspired me. I hadn't heard a female MC before that... she's real... her presence... her image... the way she does everything... she opened so many doors for us girls, MCs are real, they write their own stuff, they rap about what they know, the stuff around them." She was also influenced by her mother's Salt-n-Pepa albums and began writing poetry at age 11.[citation needed]

Going by the name of Lady Sovereign, or simply Sov — a nickname she picked up after stealing a sovereign ring from a friend’s boyfriend — she began writing songs. After she persuaded her father to buy her an old PC and she bought a microphone, she started visiting internet chat rooms. Lady Sovereign met DJ Frampster online, and they began posting 20-minute sets as the garage-grime act Heavy Like Dat.[citation needed]

During these tentative steps, Sovereign signed up for a month-long drama class, which led to a role in an educational film on truancy. She convinced the film's producers that she could record a soundtrack for the film, the demos for which landed in the hands of record producer Medasyn. He partnered Sovereign with Frost P, Zuz Rock, and Shystie for a Male vs. Female MC freestyle contest, titled "The Battle" which was released in 2003 on Casual Records.[citation needed]

Lady Sovereign decided to sign with Universal and strike out on her own in 2004. With Medasyn’s help, she released a number of solo tracks on vinyl and opened for acts like Basement Jaxx, The Streets, Dizzee Rascal, D12, and Obie Trice.[citation needed]

Her mother contracted a terminal brain tumour - this has been suggested as a contributing factor in Lady Sovereign's behaviour. On 14 March (Mothering Sunday in the UK) 2010, her mother died.

"The Battle" began a string of singles that would push Lady Sovereign into the spotlight. While "A Little Bit of Shhh!", "9 to 5", and "Sad arse Stripper" were selling well, free Internet-only freestyles like "Tango" and "Cheeky" were becoming just as popular. On 15 November 2005, Chocolate Industries released the Vertically Challenged EP, which collected most of her singles recorded to date. In April 2006 she released her second EP, Blah Blah in the UK. She released yet another EP, but was limited for US radios; Size Don't Matter!

Aside from her own records, 2005 saw Lady Sovereign appear as a guest or contributor on several projects. She began 2005 by appearing on the grime compilation Run the Road, both as a solo artist and with The Streets. When The Ordinary Boys released the single "Boys Will Be Boys", Lady Sovereign came back with a reply remix, featuring the music and chorus of the original, but with mostly her own vocals to the tune of "girls will be girls". In May 2006, she was featured on the Ordinary Boys single, "Nine2Five", a remixed version of her own "9 to 5", credited as "The Ordinary Boys vs Lady Sovereign." "Nine2Five" entered at #39 in the UK top 40 singles on downloads only, and jumped to #6 upon availability as a CD and 7" vinyl single during the week commencing 22 May 2005. This is her highest chart position to date.

Lady Sovereign capped off 2005 by meeting with the American hip hop artist and CEO of the labels Def Jam Recordings and Roc-A-Fella Records, Jay-Z. This marked her foray into the American music scene. With Usher and L.A. Reid seated next to him, Jay-Z asked for one on-the-spot freestyle from Sovereign before offering her a contract with Def Jam. With the single "Hoodie", Lady Sovereign released her full-length debut, Public Warning, on Def Jam in 2006. Lady Sovereign is the first non-American female to ever be signed to Def Jam Record Label.

On 31 October 2006, her debut album, Public Warning, was released, featuring "Random", "9 to 5", "Hoodie" and single, "Love Me or Hate Me," which was also released on the same day. The music video for the single features Lady Sovereign mocking stereotypical ideals of femininity by satirizing popular dress and mannerisms. Some of the lyrics include I'm fat, I need a diet/No, in fact I'm just too light/I ain't got the biggest breast-ises,/but I write all the best disses/I've got hairy armpits/But I don't walk around like this/I wear a big baggy t-shirt that hides that nasty shit. With the lyrics continuing in this satirical nature, Lady Sovereign continues to comment on and express her dissonance with female lifestyles in popular culture. She began an American tour on 23 October 2006 and soon after appeared on Late Show with David Letterman. In addition to her own tour, she appeared as the opening act for various artists, including The Streets and Gwen Stefani on her 2007 The Sweet Escape Tour.