Girl Thing, A1, Eternal, 3T, Damage and 5th Story took to the stage at London's Hammersmith Apollo in front of a packed out audience of fans and celebrity faces.
5th Story - a band made up of Kenzie, Adam Rickett, Dane Bowers, Kavana and Gareth Gates - performed a selection of their individual hits, including Another Level's 'Freak Me', Adam's 'I Breath Again' and Kavana's disco favourite 'I Can Make You Feel Good'.
Before the high-profile event, they expressed their thanks in a tweet, saying: "It's show time! Thank you Hammersmith for letting us do this for the first time ever live. @BigReunionITV @itv2."
Celebrities in the audience included Leigh Francis, aka Keith Lemon, and I'm A Celebrity winner Kian Egan who was cheering on wife Jodi Albert from Girl Thing.
Spice Girl Emma Bunton was also in the audience to support fiancé and Damage singer Jade Jones.
Damage performed 'Ghetto Romance' and 'Wonderful Tonight' as the crowd went wild.
Girl Thing also thrilled the crowd, when they sang their own hit 'Girls On Top', a cover of Katy Perry's 'Roar' and the controversial HearSay song 'Pure & Simple'.
Before taking to the stage, former Hollyoaks actress Jodi tweeted: "It's TONIGHT!!!!! #HammersmithApollo #Girlthing ready to rock!!! Bringing the Disco!!! Xx
"Good luck gang! Such a lovely bunch of beauties @a1official @WeAre5thStory @EternalReunion @officialdamage @TheReal3T @GirlThing2014 #RockIt."
A1 and Eternal received huge applause from the crowd, while 3T - a trio of brothers who are sons of Tito Jackson - sang their 1996 hit 'Anything' and 'Why', their collaboration with uncle Michael.
All the acts came together at the end of the show for the finale, a version of 'Spirit In The Sky' which Gareth took to No.1 in 2003.
The Big Reunion 2014: Now and then
Copyright: Rex Features