Singer-songwriter Ryan O'Shaughnessy is among the lineup, following his reinstatement into the competition last weekend after his contract with Ireland's The Voice was cancelled.
© ITV / THAMES/SYCO
© ITV / THAMES/SYCO
Basketball stunt act Face Team and 16-year-old singer Hope Murphy will also appear.
Laser harp musician Grieg Stewart, wheelchair dancers Strictly Wheels and Cyr wheel performer Billy George will also take to the stage.
© ITV
© ITV
The lineup is completed by Dalek impersonator Martyn Crofts, comedian Callum Oakley and synchronised swimming group Aquabatique.
Ashleigh & Pudsey, Jonathan & Charlotte and the Loveable Rogues will be among Saturday's finalists.
The Britain's Got Talent semi-finals conclude tomorrow (May 10) at 7.30pm on ITV1.
Photo gallery: Britain's Got Talent's fourth semi-final:
Britain's Got Talent Semi-Final 4: The Judges - Simon Cowell, Amanda Holden, Alesha Dixon and David Walliams
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Copyright: Rex Features Ken Mckay/Thames
