Sarah Harding for BGT spin-off show
Sarah, 31, will join host Stephen Mulhern on a celebrity panel.
A show source said: "Sarah is delighted. She's proven herself as an actress and comes across as bright and opinionated. She's also very easy on the eye and will inject some much-needed glamour to the BGMT cast.
"She's been offered the gig on the night of the final which, obviously, will be the biggest audience of the series so far."
The newspaper said that that there was no suggestion of Sarah taking up a judge's role on The X Factor - on which Cheryl Cole famously enjoyed a stint - despite suggestions that Simon Cowell might be looking to replace Tulisa Contostavlos.