The girl band, who won the 2011 series of The X Factor, will be performing their hit single 'Salute' while Diversity bust out a mind-blowing routine alongside them.
And to make it even more exciting, they will be joined on stage by a special guest. Ooh, could it be Cheryl Cole, who is rumoured to be performing her comeback single on BGT?
BGT judge Alesha Dixon certainly seems to think so. Earlier today, Alesha retweeted a newspaper columnist who had said: "Cheryl Cole to make live music comeback on Britain's Got Talent final #bgt #cheryl @cherylcole."
As usual, the live semi-finals - featuring a total of 45 acts - will run each night across the course of a week and the stage will also be graced by will.i.am, Ed Sheeran and The Vamps.
Former X Factor contestant Ella Henderson - who appeared in the 2012 series - will give the first performance of her debut single 'Ghost' too.
We can't wait!
Britain's Got Talent's live semi-finals will air on ITV on Monday 26, Tuesday 27, Wednesday 28, Thursday 29 May and Saturday 31 May on ITV. The live final is on Saturday 7 June on ITV.
This year's winner bags £250,000 and a coveted performance slot at the Royal Variety Performance.
Reveal is now on Google Plus! Join us here for the latest pictures, fashion and celebrity news!