The 64-year-old performed his own version of REM's Everybody Hurts.
He is now the parish priest in Oldcastle and Moylagh, Co Meath, a position he has held since 2006.
Fr. Ray Kelly went viral in 2014 with his performance of Leonard Cohen's Hallelujah.
Where have you seen him before?
Changing the lyrics ever-so-slightly, we've got to admit - it was a pretty lovely tribute for the then-newlyweds Chris and Leah.
Well he's pretty well known back in Ireland, having appearances on The Late Late Show, among others.
He also had a recording contract with Universal Music in 2014 in the wake of his YouTube fame. I think your voice is beautiful, I love the version of the song, this was everything we've been waiting for genuinely.
"This is one of my favourite ever auditions", Cowell told Fr Kelly.
Check out Fr Ray's audition here - which saw him progress to the next stage of the competition, the selection for the live semi finals.
While Britain's Got Talent can normally be full of wacky dancers and bonkers comedians, sometimes there are moments that make us well up.