EastEnders actresses Brett and Empson were the first celebrities chosen to progress, as they received the greatest number of public votes.
The pair began the show with a rendition of Lady GaGa's 'Telephone', which saw Brett wearing Coca-Cola can hair rollers and a American flag dress, and Empson in a red, white and blue outfit similar to that of Beyoncé in the song's video.
Alderton was later chosen by judges Greg Davies and Keith Lemon to compete for the show crown next month. The comedian performed a routine to Tina Turner's 'Proud Mary', wearing a wig imitating the veteran singer's hairstyle, a short, red dress, blue eyeshadow and red lipstick.
The other celebrities competing during the show were former cricketer Darren Gough, who danced to West Side Story's 'Gym Mambo', DJs David Hamilton and Tony Blackburn, who took on an energetic routine to Salt-n-Pepa's 'Push It' and Shooting Stars' Angelos Epithemiou and Ulrika Jonsson, performing to 'El Tango de Roxanne' from Moulin Rouge.
Let's Dance for Sport Relief continues next Saturday (February 25) at 7.10pm on BBC1.