Horgan-Wallace rose to notoriety in the United Kingdom when she was selected as a contestant in the seventh series of the Channel 4 TV series, Big Brother, in 2006. She entered the Big Brother House on Day 12, and became known for her clashes with fellow contestants Nikki Grahame and Grace Adams-Short, and for being voted into the "House Next Door" by the public — a secret house, where she was forced to choose who, out of five new contestants, would become new housemates. Horgan-Wallace reached the final on Day 93; she came third with 22% of the public vote. She was the highest placed female housemate of the series. It was reported that Horgan-Wallace's popularity shocked the show's producers, with tabloid sources suggesting that they had attempted to "engineer" the series' finalists, and did not expect the swing in public support for her.
In August 2010, she turned down an offer to appear in Ultimate Big Brother in order to shoot her scenes as 'Maria' in the British urban comedy movie, Anuvahood instead.
Since 2007, Horgan-Wallace has been a frequent guest on the Big Brother support shows, Big Brother's Big Mouth, Big Brother's Little Brother, and latterly, since the show's move to Channel 5 in 2011, Big Brother's Bit On The Side.
Since 2007, she has appeared in a number of episodes of Charlie Brooker's Screenwipe. She has also presented for shows such as T4. She appeared in BBC One's Test The Nation, on a team with several other Big Brother contestants. She also made a small appearance on The Charlotte Church Show. She appeared in several episodes of the Red TV series Celebrity: Stars at Work, which aired in December 2007 and January 2008. Following on from this, Horgan-Wallace signed a one series contract with Red TV to film a self-titled, fly-on-the-wall documentary Aisleyne. Four episodes were broadcast, the first being aired on 5 March 2008.
In June 2008, Horgan-Wallace made a guest appearance on a special edition of The Friday Night Project, which aired after the launch of Big Brother's ninth series. Her contributions to the show included a sketch which mocked her rivalry with former housemate Nikki Grahame. In August 2008, she made a brief cameo appearance in The Kevin Bishop Show. In October 2008 Aisleyne appeared in Channel 4 and E4's horror Dead Set, which was written by Charlie Brooker. She played herself in this show. She featured in two episodes - episode 1.01 and episode 1.05. In episode 1.05 she played a zombie version of herself.
On 2 March 2009 Aisleyne underwent a make-under for the BBC Three programme Snog Marry Avoid?, presented by Jenny Frost. She was persuaded that a more natural look suited her. In May 2009 she was interviewed for the E4/CH4 programme - Big Brother: A Decade in the Headlines, written and presented by Grace Dent.
In March 2010 she appeared as a guest diner on the Living TV programme, Celebrity Restaurant in Our Living Room. On 5 May 2011 she starred in an episode of Celebrity Hens and Stags for Wedding TV. She helped organize a stag night in Edinburgh including racing in an off-road buggy. In June 2011 she appeared as a contestant in the TV3 (Ireland) series, Celebrity Salon. She finished runner-up behind TV presenter, Alan Hughes.
In January 2012 she appeared in the third series of the Channel 4 show Celebrity Coach Trip, alongside fellow Big Brother alumna Nikki Grahame. The pair were given a red card on Day 3 of the series after clashes with older celebrities including Edwina Currie and Jean Broke-Smith. From December 2012, Horgan-Wallace became a regular guest on the Loaded TV chat show, Looser Women Live, a programme regularly hosted by her friend, the model and fellow reality TV star, Nicola McLean.
On 11 February 2015 she appeared as a claimant on the ITV daytime show Judge Rinder, in a case of unpaid debt against her fellow former BB7 contestant Michael Cheshire, winning her case.
She appeared on the Channel 5 show Celebrity Botched Up Bodies on 6 October 2016, regarding trouble with dental veneers.
On 25 March 2017, she appeared as a contributor in the Channel 5 show When Celebrity Goes Horribly Wrong.
On April 3 2017 she was featured in the Channel 4 programme How'd You Get So Rich? presented by Canadian comedian Katherine Ryan, in which she discussed her acquisition of a property portfolio.
On 22 September 2015 Horgan-Wallace appeared as a panelist on the Celebrity Big Brother's Bit on the Side after-show and got into a heated argument with fellow panelist, Farrah Abraham. The show was taken off air 10 minutes early after a "clash" between panellists. Abraham and Janice Dickinson were given police cautions. Horgan-Wallace was to face trial on charges of common assault and criminal damage, but according to the Daily Mirror, on 29 January 2016 the CPS dropped all charges.
In 2006, she had a small part in the film Rollin' with the Nines.
After Big Brother, Aisleyne made numerous personal appearances in nightclubs around the UK. She hosted a show for the online radio station, Invincible, was a guest commentator on BBC's Asian Network and made several guest appearances on Choice FM's 'Morning Vybe' show.
She worked as an agony aunt for More magazine and wrote a weekly column for Reveal magazine covering Big Brother 8 as well as a daily blog on their website. She reprised this role for the programme's ninth and tenth series.
In September 2007, it was announced that she had taken control of her own career via her management company, Aisleyne Ltd, along with co-director Richard Skeels.
On 10 February 2008 Aisleyne released a fashion range named "Unique by Aisleyne". She worked with the "high-end" fashion distributors Unique Collections Ltd, to design and produce the outfits. A complementary swimwear range was launched a few weeks later.
It was announced on 24 April 2008, that Mainstream Publishing had bought the right to publish her autobiography, entitled Aisleyne: Surviving Guns, Gangs and Glamour. This book was published on 7 May 2009. The launch party held on 6 May was attended by various celebrities, including Jodie Marsh, Charlie Brooker and Nate James.
On 24 and 27 March 2009, she co-hosted a radio show on SMUC Radio with Eamonn McCrystal.
Horgan-Wallace plays the character 'Maria' in the British film comedy Anuvahood, which was released in the UK on 18 March 2011.
On 10 June 2011 she was a judge in the Miss Universe Ireland beauty contest in Dublin.
Horgan-Wallace plays the character of 'Jasmine' in the forthcoming low-budget British horror movie, Serial Kaller, which was filmed in April and May 2013.
In March 2014 she launched her own celebrity boot camp named Aisleyne's Booty Camp, based in a Country House near Grantham, Leicestershire.
In October 2016, Horgan-Wallace launched her own fitness app titled Aisleyne 7 Minute Workout, which was released on the Apple and Android Play Store platforms.
Horgan-Wallace is a patron of Brain Tumour UK and acted as an ambassador for Club4Climate, an initiative based around parties in London's West End and elsewhere that aimed to prevent climate change. In 2007, she completed the London 10 kilometre run to raise money for Brain Tumour UK, and she completed the same event on 6 July 2008.
She has been involved with the NHS Stop Smoking campaign in association with Cancer Research UK, and has given her support to No Smoking Day each year since 2008. She also became involved in the "Put the Knives and Guns Down!" campaign encouraging teenagers to get off the streets and stop shootings and stabbings.