The Pilton-born 46-year-old, billed as "the new Sinatra" was asked by producers to audition for the show next month, and is also set take to the stage at the Jam House in Queen Street tomorrow night with a 15-piece band, after selling out the 600-seat venue in August.
Mr Innes' love of music - and particularly Sinatra - was nurtured by his father John.
He said: "I grew up listening night and day to my dad's collection of Sinatra, Sammy Davis and Dean Martin records. You could say I'm in awe of Frank.
"I was playing saxophone in bands around Edinburgh in my teens and twenties, scraping a living, before I joined the army at 28, primarily as a musician."
As well as playing for the Black Watch band and the Band of the Royal Regiment of Scotland, he trained as a combat soldier and in 2003 completed a tour of duty in Iraq.
He said: "I was with the Black Watch, in time to become principal saxist in their band, when I did a six-month tour with them in Iraq. We saw a fair bit of action.
"In Hong Kong, we formed a group within the band. The guys heard me sing and said I sounded a bit like Sinatra.
"I took it from there and I played and sang at several high-profile gigs - Princess Anne at the Royal Scots and New clubs, Holyrood garden parties and the Tattoo."
He left the army in June after 18 years, and decided to make a living from music on Civvy Street. His brother's girlfriend entered him into Britain's Got Talent and brother John, an opera singer, sent a DVD of them performing together.
Producers have now asked them to audition for the show later this month. The brothers hope to duet on My Way for the audition, and Mr Innes said: "I feel quite relaxed about it - it should be fun."