In the emotional chat, which will air in full later this week, the singer reveals she suffered years of abuse at the hands of her own mother, Marie O’Connor.
"She was not well. She was very, very, very not well. I would say she was possessed. Although I’m not sure I believe in such things," the Nothing Compares 2 U hitmaker told Dr. Phil.
"She ran a torture chamber. It was a torture chamber. She was a person who took delight and smile in hurting you," she explained, before revealing she ran away from home when she was just 13.
"I ran away. She used to make me say over and over ‘I am nothing. I am nothing’ or else she’d beat me," Sinead added.
When the star was 19 years old, her mother died in a car crash.
Since making headlines last month after posting a troubling Facebook video, Sinead says she's not mentally unstable.
"I am fed up of being defined as the crazy person, the child abuse survivor," she told Dr. Phil.
She criticizes her family for allegedly not being there for her.
"What happened was I had been writing to my family, begging letters and angry letters. I thought it would be better, maybe my family might [reach out to me], if they saw how I’m feeling, they would relate to it," she said.
"I obviously want to be really careful cause I love my family and I don’t blame them. It’s not easy for families of mentally ill people. We can be difficult," she explained.
She also tells Dr. Phil: "I'm changing my name. Sinead O'Connor is gone."
In the worrying video message, Sinead said the only people in her life were medical professionals.
"There's absolutely nobody in my life except my doctor, my psychiatrist – the sweetest man on earth, who says I'm his hero – and that's about the only thing keeping me alive at the moment ... And that's kind of pathetic," she claimed at the time.
The Irish singer-songwriter said she hoped her video might provide some help to others struggling with mental illness.
"I'm fighting, fighting, fighting, fighting -- like all the millions and millions that I know I'm one of -- to stay alive every day," she added. "Which I'm doing because I love the people who are doing this to me. I'm not still alive for me. If it were for me, I'd be gone straight away back to my mum."
Since the video was posted, a statement confirmed Sinead was "safe" and not "suicidal" and "receiving the best of care."
If you, or someone you know, would like to have a free, confidential chat with someone they can trust, contact Lifeline on 13 11 14 or visit their website www.lifeline.org.au.