Kevin Cartwright, a 44-year-old full-time carer from Staffordshire, won the £1,000,000 prize after choosing red in the final wheel spin.
"I'm in complete shock," he said after his win. "I still can't believe it's just happened. I watched the ball land on the black and I thought that was it. I couldn't focus. I thought I was in a dream, I'm shocked.
"I nearly never turned up at Wembley for the first round because [my partner] Nicola wasn't feeling herself but she encouraged me to go. The first thing I'm going to with the money is take her on holiday to the US.
"The icing on the cake was Simon Cowell came up to us on stage and congratulated me and said that had him on the edge of my seat, the way that ball was spinning."
Cartwright's win follows 31-year-old bricklayer Nathan Hageman's success last night, when he also correctly predicted that a giant roulette wheel would land on red.
Red or Black? continues tomorrow night at 8pm with musical guests Il Divo.