Tulisa was born on 13 July 1988 in Camden Town, London, to Anne Byrne (who, with her three sisters, was a member of the 1980s band Jeep), who was born in Sheffield, South Yorkshire to Northern Irish parents, and a Greek Cypriot father Plato Contostavlos (who was at one time a member of Mungo Jerry). When Tulisa was five, her mother, who has bipolar disorder and schizoaffective disorder, was sectioned under the Mental Health Act. At age 14, with support from her uncle, Byron Contostavlos, N-Dubz's former manager, she enrolled at Quintin Kynaston School in St John's Wood but later attended Haverstock Secondary School where she did not sit her GCSE examinations.

Dappy and Fazer, who had already started rapping together, decided they wanted a female voice in the group, which was called the Lickle Rinsers Crew at the time, and so invited Tulisa to be part of the group. They started performing together as a group around Camden from young ages. For N-Dubz's second album, Tulisa did a solo song called "Comfortable". Performing as the Lickle Rinsers Crew, they released the singles "Bad Man Riddim" and "Life Is Getting Sicker by the Day", which became hits on pirate radio stations. After Lickle Rinsers Crew, they then became NW1, after the area they hail from, making their first music video in 2005 for the track "Everyday Of My Life", which received airplay on Channel U, recording more demos as NW1 such as "Don't Feel Like Moving", "Girl On Road" and "Livin Broke". Their first single to be released was "You Better Not Waste My Time", which was available for download only until their 2006 self-released single, "I Swear", which gained them their first mainstream notice. It wasn't until 2007's "Feva Las Vegas" (also self-released) that the group appeared on the UK charts, peaking at No. 57.

In 2007 and 2009, Tulisa played the role of Laurissa (a cocaine addict who is in R&B group The Fam) in the TV series Dubplate Drama. She also played Shaniqua in the straight-to-DVD British comedy, Big Fat Gypsy Gangster, and made her big screen debut in Arjun Rose slasher Demons Never Die.

In May 2008, a song entitled "Ouch" surfaced along with a music video. The video for "Ouch" attracted over 4 million viewers on networking site YouTube in just over a month after release. On 6 August 2008, it was announced that the group had left Polydor Records and had signed to All Around the World records. The label predominantly specializes in dance music; however, they have occasionally released hip hop records such as Ice Cube's You Can Do It. The press release stated that the label would be releasing "Ouch" as the group's first single on the label in September 2008. The group's first album, Uncle B, was released on 17 November 2008. The album includes "You Better Not Waste My Time", "I Swear", "Feva Las Vegas", "Love for My Slums", "Ouch", "Defeat You" and "Papa Can You Hear Me?". "Strong Again" was touted as the third single to be released from the Uncle B album on 16 February 2009 and a music video was made, before the physical CD released of the song was cancelled for unknown reasons. The song charted for five weeks in the UK Singles Chart, peaking highest at number 24.

The lead single from the group's second album titled "I Need You" was released on 9 November 2009 and charted at No. 5 in the UK Singles Chart. The album Against All Odds, was released on 16 November 2009, and charted at No. 6 in the UK Album Chart. The album went platinum within approximately 2 months of release. The second single, "Playing with Fire" features R&B/pop musician, Mr Hudson. The song reached No. 15 in the UK Charts on album downloads alone; however, when the single was released, it fell to No. 16, reaching a new peak at No. 14 the week after. The music video for the third single taken from the album, "Say It's Over", was released on 5 March 2010 on Channel AKA. The single reached No. 27 on album downloads alone before the single was released.

In 2010, Tulisa was on a BBC programme called Tulisa: My Mum And Me describing her life before N-Dubz looking after her mother.

On 30 May 2011, Tulisa was confirmed to replace Cheryl Cole as a judge for the eighth series of The X Factor, alongside original panelist Louis Walsh, and new judges Gary Barlow replacing Simon Cowell and Kelly Rowland replacing Dannii Minogue. The first public auditions began on 23 June 2011, with the new judging panel being sighted together for the first time. Tulisa mentored the Groups category and mentored 2 Shoes, Nu Vibe, The Risk, and Little Mix during the live shows. After three out of four of her acts were eliminated in the first five weeks of the competition, Constostavlos was left with Little Mix. The group then went on to become the most successful girl band in The X Factor history, having avoided the final showdown every week and winning the show in the process, making them the first group to do so in the show's eight-year history. Tulisa returned for the ninth series in 2012, alongside Walsh, Barlow and Nicole Scherzinger, who replaced Rowland and finished as the winning judge with James Arthur. Tulisa mentored the "Girls", a category made up of female contestants aged 16–28, which included Jade Ellis, Lucy Spraggan and Ella Henderson.

In July 2012, she settled a legal action against Edwards. It was later reported that her Lawyer was still pursuing action against Edwards' former manager Chris Herbert, who had his job as a consultant on The X Factor suspended.

On 4 June 2013, Tulisa was arrested by police on suspicion of supplying class A drugs and bailed to a date in July 2013. Two residential properties had been searched as part of the investigation. She was formally charged on 9 December with "being concerned in the supply of Class A drugs" and appeared at Westminster Magistrates' Court on 19 December where she denied being involved with the supply of 13.9 grams of cocaine. She was granted unconditional bail and then appeared at Southwark Crown Court on 9 January 2014. The trial date was set for 14 July 2014. The case was dismissed as the judge believed prosecution witness Mazher Mahmood had lied to the court. In April 2015, Mr Justice Nicholas Kearns, President of the Irish High Court, described her as having been "cruelly deceived in a shabby sting operation", but dismissed her attempt to sue the Irish Sun for defamation over the case as he was "astounded" by the delay in initiating legal proceedings.

In July 2014, her documentary Tulisa: The Price of Fame premiered on BBC Three to a moderate success, attracting 615,000 viewers (3.8% of the audience within its time slot). On 9 August 2014, it was confirmed that the singer would return to The X Factor for its eleventh series as Louis Walsh's guest judge during the judges' houses stage in Bermuda. In October 2014, Tulisa announced her new single "Living Without You". Its release was initially planned for 7 December 2014, however it was later postponed to 4 January 2015. The single peaked at number 44 on the UK Singles Chart. On 13 December 2014, Tulisa returned to The X Factor as a guest judge for the first night of the series 11 final alongside Louis Walsh, Simon Cowell and Cheryl due to Mel B being ill.

On 2 September 2016, she released the single "Sweet Like Chocolate", which featured Akelle. She has also confirmed that she has signed with an agent in an attempt to begin a career as a film Actress.