The duo host the new ITV1 gameshow, which will be staged live over seven nights, beginning this weekend. The contestants competing in the studio have been whittled down through early stages filmed at Wembley Arena and other locations around the UK, including the Coronation Street set.
"Every show is split into three different stages," Dec explained to TV Times magazine. "First, there's the arena stage, where an audience at the Red or Black? arena in Wembley watches challenges and stunts with a Red or Black outcome.
"If they get it right, they move through to the location stages until we have a final eight contestants. These eight contestants will guess the outcome of more Red or Black challenges in the studio, where one will get to play for £1 million, live on ITV."
He continued: "All the way through it's about luck; there's no skill, there's no talent involved, you don't have to sing a song or have a snake wrapped around your neck. Basically, if your luck holds out for ten different games, you'll be playing for a million pounds.
"Each night, someone could walk away with a million pounds or leave with nothing. We could have seven millionaires, we could have none - it's going to be a rollercoaster of a week!"
Teasing the challenges viewers will see, Donnelly said that some of the "very large scale" rounds were "pretty risky" to pull off.
Ant added: "We're trying to get those stunts and games that you've never seen before on live television. It will be very risky - but unmissable!"
Red or Black? kicks off on Saturday at 7pm on ITV1, featuring Leona Lewis performing her new single 'Collide'.
> Ant and Dec kick off ITV's Red or Black?
> Louis Walsh fires David Hasselhoff 230ft into sky on Red or Black?
Watch the trailer for Red or Black? below: