Protheroe now performs under the title Vince Kidd and is one of the acts who aims to impress coaches will.i.am, Sir Tom Jones, Jessie J and Danny O'Donoghue on Saturday night's second auditions show.
Futureproof - who were formed at the Boot Camp stage of X Factor - also featured Aaron Delahunty, Adam Chandler, Richard Wilkinson and Sean Rumsey. They were mentored by Simon Cowell and reached the live show rounds.
Under his Vince Kidd moniker, he has also collaborated with X Factor winner Leon Jackson on a single titled 'Sick Love'.
Other acts on this week's Voice UK auditions show include fellow X Factor rejects Barbara Bryceland and Heshima Thompson and former Five Star singer and '80s pop act Denise Pearson.
The Voice UK airs on Saturday (March 31) at 7pm on BBC One.
Watch a Futureproof performance on X Factor:
Photo gallery - The Voice episode 2: