Olly Murs and Scott Mills, comic Omid Djalili, Outnumbered's Tyger Drew Honey, Dani Harmer and The Fast Show's Arabella Weir complete the lineup for the third heat.
Popstars Tinchy Stryder and Pixie Lott will perform their track 'Bright Lights' on the show, while singer Chris Isaak is also confirmed to perform.
Guest judges on the third show will include musical stand-up Tim Minchin and comic and former Let's Dance performer Katy Brand.
Alex Jones and Steve Jones continue to host the fundraising reality series, which saw Laurie Brett & Tameka Empson and Terry Alderton progressing to the final last weekend.
Let's Dance for Sport Relief continues this Saturday (February 25) on BBC One.
> Laurie Brett, Tameka Empson, Terry Alderton in 'Let's Dance' final
> Vic Reeves, Rufus Hound to judge 'Let's Dance for Sport Relief'