Matt Phillips rejected overtures from England caretaker manager Stuart Pearce in favour of representing Scotland.
The 20-year-old Blackpool winger, who was born in Aylesbury, was called up by Scotland boss Craig Levein after his Scots-born grandfather tipped off a journalist about his eligibility.
The England Under-20 international has lodged his change of allegiance with FIFA and is committed to Scotland.
Phillips said in a number of Scottish newspapers: "I spoke to Stuart Pearce personally, because it had to come from me.
"A lot of people might have sat around and waited (for England). But I told him I wanted to come away and play for Scotland.
"I had a number of conversations with him but I haven't just made this decision in the past month. It's been an ongoing thing and something that's always been at the back of my mind that one day I'd play for Scotland.
"I believe enough in my ability to think that one day I would have played for England. But I'm not looking at that now.
"Even if England asked me to play for their Under-21s now, my mind is made up. I fully believe it's the right decision."
Phillips, who yesterday modelled Scotland's new white away strip, has pulled out of Wednesday's friendly in Slovenia after missing Blackpool's weekend win over Bristol City.
But he is expected to be included in Levein's squad when Scotland face the United States in Florida on May 26.
He added: "Unfortunately I've had to pull out of the Slovenia game because of a slight niggle in my hamstring but if I'm selected for the next squad, hopefully I can get my first cap then.
"I just felt I still needed to come up here this weekend, meet the rest of the lads and show I am committed to Scotland."