During the group's break, Harding began acting, appearing in Bad Day, the BBC television film Freefall, Run for Your Wife and St. Trinian's 2: The Legend of Fritton's Gold.

In 2015, Harding briefly appeared in the soap opera Coronation Street and released her first extended play record Threads.

In August 2020, Harding announced that she had been diagnosed with advanced breast cancer; she revealed in March 2021 that her condition was terminal.

[8] She then worked as part of the promotions team for two nightclubs in The Grand Central Leisure Park in Stockport, as a waitress at Pizza Hut, a van driver, debt collector and as a BT telephone operator.

She also toured North West England performing at pubs, social clubs and caravan parks to support herself.

Harding also entered FHM's High Street Honeys 2002, the magazine's national beauty contest.

Each week the contestant polling the fewest phone votes was eliminated, until the final line-ups of the groups emerged.

[13] The group released their debut album Sound of the Underground in May 2003,[14] which entered the charts at number two and was certified platinum by the British Phonographic Industry (BPI) later the same year.

Girls Aloud's collaborations with Brian Higgins and his songwriting and production team Xenomania earned the group critical acclaim,[17] due to an innovative approach to mainstream pop music.

The group became one of the few UK reality television acts to achieve continued success, amassing a fortune of £30 million by May 2010.

[18][19] In 2006, Harding signed a £100,000 deal to model Ultimo lingerie, following the likes of Penny Lancaster, Rachel Hunter and Helena Christensen.

[21] In July 2009, Girls Aloud announced they would take a year-long hiatus to pursue solo projects, but would reunite for a new studio album in 2010.

[23] Harding appeared in the BBC television film Freefall, written and directed by Dominic Savage.

[25] Company magazine said that "Sarah Harding showed she's got real acting potential in her convincing, but fleeting performance.

[27] Harding worked with Girls Aloud producers Xenomania to record three solo tracks for the film's soundtrack – "Too Bad", "Make It Easy" and a cover of David Bowie's "Boys Keep Swinging".

Harding then filmed Run for Your Wife in which she played one of the wives of the lead character, John Smith.

The character made a few appearances in July and August 2015 as her marriage to Robert disintegrated when he began an affair with ex-wife Tracy Barlow (Kate Ford).

[43] Harding took part on the third series of The Jump on Channel 4 in early 2016, withdrawing on 26 February (Week 5) after tearing a ligament in her knee during a training session.

[44] In Autumn 2016, Harding appeared alongside Andy Moss in a UK tour of Ghost: The Musical.

[46] On 18 March 2021, Harding released a memoir, Hear Me Out, documenting her life and career as well as her cancer diagnosis.

[47] On 24 March 2021, Harding released her final single, "Wear It Like a Crown", which she had recorded ten years earlier.

[56] In October 2011, Harding entered a rehab centre in South Africa, citing alcohol dependence and depression.

[60] Harding wrote a memoir, Hear Me Out, which was published in 2021, documenting her life and career as well as her terminal diagnosis.