The show featured chart-topping bands who were big in the UK pop music scene between the 1990s and early 2000s, and the programme followed them as they reunited for the first time in a decade and went through their two weeks of intensive rehearsals before finally stepping back on stage for a comeback performance.

The second series, which premiered on 6 February 2014, featured 3T, A1, Damage, Eternal, Girl Thing, and a supergroup called 5th Story, which consisted of Kenzie from Blazin' Squad, Dane Bowers from Another Level, and former soloists Adam Rickitt, Kavana and Gareth Gates.

Kelpie said: "To reunite these bands, tell the stories of what has happened to them since their heyday and follow them as they prepare to step back on the stage for the first time in a decade is a dream come true."

Filming for the show began in October 2012, featuring the members of each band telling their individual stories about their bandmates and displaying their own personal lives nowadays, and later meeting together again for the first time in several years.

[citation needed] Additionally, Five only reunited as a four-piece as founding member and lead singer Jason "J" Brown backed out at the last minute, claiming that he no longer wants to be in the public eye, having initially attended previous meetings for the show.

[citation needed] The first three episodes featured Five, Liberty X, Atomic Kitten, 911, Honeyz and B*Witched telling their backstories of their time in their respective groups and about their lives since splitting up.

When asked why they chose to join the comeback gig, Blue said: "Phil Mount, The Big Reunion's producer, has always been a long-time supporter of the band, giving us our first TV break, he really wanted us to be surprise special guests announced halfway through the series and to perform on the Hammersmith Apollo show.

This sounded like a lot of fun, giving us the perfect chance to perform together again in the UK for our fans and reconnect with the other acts, many of whom friends of ours and started out around the same time as us.

It also gives an insight into the work undertaken by Text Santa charities Age UK, Barnardo's, BeatBullying, the British Heart Foundation, CLIC Sargent and Help the Hospices.

[11] Groups rumoured to be reuniting for series 2 included Big Brovaz, Hear'Say, S Club 7, Busted, Mis-Teeq, East 17, All Saints, Eternal, A1, Cleopatra and Another Level.

[15] On 27 December 2013, ITV announced that the six bands taking part in the show's second series would be A1, Eternal, Damage, 3T, Girl Thing and a supergroup called 5th Story, comprising Blazin' Squad's Kenzie, Another Level's Dane Bowers, and former soloists Gareth Gates, Adam Rickitt, and Kavana.

[21] After watching the first episode, which focused on the rises and falls of Five and Liberty X, Adam Postans of MSN said: "I'll be honest; I tuned in to this series opener to take the merciless mickey out of a bunch of pop has-been wannabes (come to think of it, 'Has-Been Wannabes' would have been a brilliant name for the losing quintet on the original ITV talent show, Popstars)...So I'm delighted and surprised to say that The Big Reunion wasn't the tiresome, drawn-out hour I'd assumed it would be..." Postans called it: "A surprisingly sober tale of the downfalls of being a pop star.

"[23] Of the third episode, which focused on the rises and falls of B*Witched and Honeyz, Frost said: "This week's 'Big Reunion' showed the strength – AND shortfalls – of girl power, and shared two more of life's harsh lessons along the way.

The sort of thing I lap up at home with my ankles raised, eating noodles, while you are possibly ironing your own face to stay alert during that new Poliakoff five-parter.

[28] The overnight audience fell sharply to 670,000 for the third episode (but official figures were 941,000), being beaten in its timeslot by Junior Doctors: Your Life in Their Hands on BBC Three.

[33] The ratings shot back up for the final episode, as an audience of 974,000 tuned in to watch the highlights and behind-the-scenes action of the Hammersmith Apollo concert.

[45] On 11 February, it was confirmed that, following high ticket demands and the popularity of The Big Reunion, a UK tour would be taking place from 3–14 May 2013.

[51] For a special Big Reunion "End of the show-show" segment on Ant & Dec's Saturday Night Takeaway on 23 March 2013, Five, Atomic Kitten and Blue all performed one song each, creating a medley.

[52] To coincide with the reunion, Ant & Dec themselves returned to their 1990s pop act PJ & Duncan for a performance of their song "Let's Get Ready to Rhumble",[52] which reached number one on the UK Singles Chart the following week.

[citation needed] On 20 March, it was announced that the boy bands from both series (Five, 911, Blue, A1, 3T, Damage and 5th Story) would go on The Big Reunion Boyband Tour in October 2014.

The bands covered Wizzard's "I Wish It Could Be Christmas Everyday" to raise money for Age UK, Barnardo's, BeatBullying, the British Heart Foundation, CLIC Sargent and Help the Hospices.

On 11 February 2014, it was announced that a two-disc Big Reunion compilation album would be released, featuring singles by bands from both series of the show.