And here's a glimpse of Blue in rehearsals for the concert at London's Hammersmith Apollo.
Blue join B*Witched, Liberty X, Atomic Kitten, Honeyz and 5ive on the lineup and the show, which airs on ITV2 on Thursday nights.
The series has followed the reunion of the 90s and early 00s groups as they prepare to hit the road again for a tour.
The success of the show has seen an expanded arena concert in May, with gigs at venues including London's O2 Arena.
However Blue aren't exactly getting back together as the group have already had an attempted reunion when they returned for Euro vision, which was followed by a new album (in South Africa, admittedly).
Are you going to tonight's gig or one of the future tour dates? Add your comments below!
Browse pictures of Blue in rehearsals below!