Willoughby, who will co-host the Saturday night series with Reggie Yates, spoke about her work on the programme during a showbiz segment on This Morning.
"The difference [with The Voice] is, it's a blind audition, the coaches can't see the contestants when they come on stage so they judge them purely on their voice and their voice alone," said the presenter.
"It's really feel-good and the judges are incredible."
Commenting on reports that auditioning acts had appeared on other reality shows such as The X Factor or previously had record deals, she added: "I can't say too much but there have been people that have auditioned that I've known..."
Jessie J, will.i.am, Tom Jones and Danny O'Donoghue were revealed as coaches on The Voice at the end of 2011. The series launches in the spring.
> Former 'X Factor' hopeful Joelle Moses auditions for 'The Voice' UK
> 'The Voice' UK coaches form supergroup at London auditions
Watch the BBC's teaser trailer for The Voice UK: