The late Irish singer-songwriter gave the psychological drama permission to use The Magdalene Song and it aired at the end of the last episode on Sunday.
The six-part series takes a look at a mysterious death in the wake of the Magdalene laundries scandal, which saw women talk about being detained against their will and forced to give up their children.
O’Connor – who died in July aged 56 – spoke openly about the abuse she faced while spending more than a year in a Magdalene laundry as a teenager.
According to Chrysalis Records, the use of the song was proposed by her producer, the Belfast DJ and composer David Holmes, and was “approved by Sinéad before her passing”.
Holmes told the Observer: “The first half of the track is completely heartbreaking and the second half is pure defiance.
“I stripped the song away to just Sinéad’s voice and then let the full power come in for the second half.
“It’s incredible how the meaning of the song came together with this story. It was just meant to be. There’s a certain magic when you bring music to an emotive story.”
In the BBC series, Tipperary actor Daryl McCormack stars as Detective Colman Akande opposite British actress Ruth Wilson – who takes on the role of Lorna Brady.
The show follows Lorna, who has suffered from bouts of sleepwalking after being put in the Catholic institution as a teenager when she became pregnant, as Colman investigates the death of a priest.
Holmes said: “In the lyrics, Sinéad was trying to say, I think, that though she’d been through great turmoil, it would not stop her being who she wanted to be.
“She never really spoke about the meaning of her songs. She used to joke that she would often tell people that her songs were about something completely different to what they were about.”
He also said that his “big regret” is that O’Connor, who protested against sexual and physical abuse in the Catholic Church when she tore up a picture of Pope John Paul II on United States TV show Saturday Night Live in 1992, would not see the series.
In August, as the late singer’s funeral procession passed by her former home in Bray, Co Wicklow, a guard of honour was made by survivors of Magdalene laundries and mother and baby homes.
Organisers estimated about 100 people who had been affected by the Catholic Church travelled to honour the Dublin-born singer – who was found unresponsive by police at her southeast London home on July 26th.
She is buried in a South Dublin plot called The Garden. – PA