Ameobi, aged 19, came off the substitutes' bench in the 11th minute as an early replacement for the injured Nathan Delfouneso, and played a key role in the Young Lions' 5-0 victory over Iceland on Thursday night.
"It was amazing to make my international debut," the Newcastle-born youngster told nufc.co.uk.
"It hasn't really sunk in yet. It's been an amazing few months for me. I've been given the opportunity to play for Newcastle, and I've now had the opportunity to play for England Under 21s. It's been amazing.
"I couldn't quite believe what happened last night. I thought it would be a quiet night for me, and that I may get ten or 15 minutes at the end if I was lucky. But one of the boys got injured and I got my opportunity.
"I wasn't nervous. I thought I would, but I was quite confident in my ability and just wanted to get out there and do well for the team."