The Dubliner insists the mental health issues she grew up with would have taken over her life had it not been for prayer and song.
In a new interview for Oprah Winfrey's Where Are They Now? interview show, which airs in America on Friday, O'Connor explained: "To me music is the holy spirit. I was a person who was going to jail. I used to steal and if I hadn't found music I would be in trouble.
"It wasn't open to me to be a priest because I was a girl, which is the only other thing I would've wanted to do. To me prayer is dreadfully important; I'm not of any specific religion. I sort of believe in everything and nothing but prayer is an enormous part of my pre-ritual everywhere we're going.
"I even have the word 'pray' on my monitor, so if I get nervous (during a gig) I can focus on that."