The former Spice Girl has had a number of small hosting roles over the years, but the new singing contest will be her first major presenting job.
Don't Stop Believing - billed as Glee meets The X Factor - will follow the search for Britain's best musical performance group.
Speaking of her new position, Bunton commented: "Like millions of others I'm currently obsessed with musical performance groups so I am beyond excited. It'll be an unmissable, all-singing, all-dancing spectacle."
According to The Sun, more than 3,000 groups have already applied to take part in the programme, which is to air over the summer.
Hopefuls can continue to apply via Five's website until May 28.