has announced she has converted to Islam, and changed her name to the Arabic word for “martyr”.
The Nothing Compare 2 U singer, 51, tweeted a picture of herself wearing a hijab.
Mum-of-four Sinead was ordained a priest by a Catholic sect during the 1990s.
But the Irish singer has changed faiths and her name to Shuhada Davitt.
“This is the natural conclusion of any intelligent theologian’s journey.
“All scripture study leads to Islam. Which makes all other scriptures redundant.
“I will be given (another) new name. It will be Shuhada.”
Last Friday she posted a video of herself singing an Islamic call to prayer.
Sinead changed her name last year to Magda Davitt, saying in an interview that she wanted to be “free of parental curses”.
In the past, she has said in interviews that her Christian faith has helped her overcome personal turmoil.
But in 2011 she labelled the Vatican a “nest of vipers” over alleged child sex abuse.
Last year, Sinead O’Connor sent a sexually explicit message to Russell Brand after he offered her mental health support.
Brand sent a supportive message to the 50-year-old on YouTube, saying that following a public breakdown she needed “connection, meaning, purpose, love and a bit of time, really”.
She replied: “Could also do with a jolly good rogering, frankly. The last man who touched my body took out my reproductive system two years ago.
“So if you really wanna be part of my healing journey, c’mon, horse it into me, boss.”