Samantha Barks and Trevor Dion Nicholas are also on the panel, with the special due to film and air later this month.
“I love singing though I haven’t sung in front of an audience since university,” Peston said.
“And I have always adored old Broadway and Hollywood musicals, a passion I inherited from my late dad.
The other celebrity contestants are W1A star Jessica Hynes, Bradley Walsh’s actor son Barney, Judge Rinder’s Robert Rinder, Good Morning Britain’s Dr Ranj Singh and EastEnders star Luisa Bradshaw-White.