The 35-year-old singer is a talent show veteran, having previously appeared on 2001 BBC show "Popstars", where he formed group Liberty X with Michelle Heaton, Tony Lundon, Jessica Taylor and Kelli Young.
After his victory was announced, the father of two said: "I can't believe it. I'm so grateful to everyone who has voted for me. I couldn't have dreamed this would happen, especially at my ripe old age."
In the early 2000s Simm had enjoyed 10 consecutive top 20 singles with Liberty X. But after the group split in 2007 he had been reduced to 100 pounds a night gigs to provide for his family.
Simm was mentored in the competition by Kaiser Chief's frontman Ricky Wilson.