A spokesperson for Southwark Coroners Court told Express.co.uk: “This is to confirm that Ms O’Connor died of natural causes. The coroner has therefore ceased their involvement in her death.”
Police did not treat her death as suspicious when she was found unresponsive.
The confirmation comes after her friend claimed she could have died from a “broken heart” after the death of her teenage son.
Sinead’s friend and producer David Holmes, 54, who was working with her on her final album at the time of her death, said in the new RTÉ documentary Sinead: “Even though Sinead was this incredibly resilient survivor, I totally believe that people can die of a broken heart.”
Belfast-born David spent five years collaborating with Sinead on what turned out to be her final album, No Veteran Dies Alone, after the pair met at the late Shane MacGowan’s 60th birthday celebration at Dublin’s National Concert Hall in 2018, where Sinead performed alongside singers including Nick Cave and Bono.
David said about their meeting: “We ended up backstage. I just stopped and introduced myself and said, “My name is David Holmes, you probably have no idea what I do or anything about me but I would love to make an album with you about healing.
“At that moment wasn’t a good time for Sinéad – everybody knows she had mental health issues.
“I needed healing myself. I was going through my own experience. It’s amazing what the right song or piece of music can do.”
David and Sinead ended up recording nine tracks together before her death.
Singer Christy Moore, 78, also appears in the new documentary on the singer, which aired on Monday in the UK, and tells how her death was a “terrible loss”.
The show covers the ups and downs and controversies of Sinead’s life, including the row that erupted when she famously tore up a picture of Pope John Paul II live on American TV in 1992 in protest at the Catholic church’s cover-ups of child abuse.