The singer-songwriter performed his own composition at his audition on Saturday's show (March 31) for an unnamed girl that he was in love with.
The 'No Name' girl was later revealed to be his close friend Katie Lucia Keegan, who confirmed her identity on Twitter.
O'Shaughnessy revealed that Keegan was unaware of his audition but was "really happy" for him.
"She told me that she was flattered and she was really happy for me," he told Daybreak. "We're going to stay friends and just see what happens.
"Over the years she's always known that I've felt a lot of feelings for her but I think she's happy."
On when she found out about the audition, he said: "She didn't know, I told her I'd gone for it, and that I sang one of my own songs, but she didn't have a clue [it was about her]."
Speaking about the track's potential release, he added: "Hopefully if things go well in the show, I might be able to record it and get it released."
O'Shaughnessy was recently said to be in trouble after it was revealed that he had also appeared in The Voice of Ireland.
Watch Ryan O'Shaughnessy perform 'No Name' on Britain's Got Talent below: