The Glasgow-born singer and actor was found dead in his US apartment, in Rochester, Minnesota, on August 11 at the age of 41.
The Southern Minnesota Regional Medical Examiner’s Office has confirmed that Darius died from “inhalation of chloroethane” in its report.
Autopsy documents obtained by the PA news agency listed “toxic effects of chloroethane” as well as “suffocation” as having contributed to his death.
Darius Campbell Danesh's cause of death confirmed
The death was also ruled an accident by the medical examiner.
A statement released by Campbell Danesh’s family previously said local police had found “no signs of intent or suspicious circumstances”.
Darius rose to fame on ITV talent shows Popstars and Pop Idol 20 years ago.
He came third on Pop Idol, following both singers Will Young and Gareth Gates in 2002.
The beloved Glasgow-born singer became a household name after his theatrical take of Britney Spears's Hit Me Baby One More Time.
Following his Pop Idol and Popstar appearances, he went on to become a West End star.
He appeared in musicals like Chicago and the Oliver Award-winning Guys and Dolls.
A statement was released by his family breaking the news, said: “It is with great sadness that we announce the passing of Darius Campbell Danesh. Darius was found unresponsive in bed in his apartment room in Rochester, Minnesota, on August 11 and was pronounced dead in the afternoon by the local medical examiners’ office.
“The local police department have confirmed that there were no signs of intent or suspicious circumstances. The cause of his sudden death is unknown at this stage while medical examinations continue.
“We ask that you kindly respect our wishes for privacy at this time whilst we come to terms with the tragic loss of our son and brother.”
Campbell Danesh lived in the US and found love with Canadian actor Natasha Henstridge, whose films include sci-fi hit Species.
They married in 2011 at the San Ysidro Ranch in Santa Barbara, California, but were divorced a few years later.
Fans and famous faces have flooded social media with tributes following the news.
Fellow Pop Idol stars Will Young and Gareth Gates paid tribute to the singer after his death was announced, describing him as “driven, courageous and gentle”.
In a heartfelt tribute, Young, 43, wrote: “For the past few days my thoughts have been with Darius’s family and will continue to be so.
“I found this picture a while ago taken during Pop Idol. If there was ever an example of not giving up on your dreams then Darius is top of the pile.
“Driven, courageous and gentle. My love goes to his family at this time x”
Gates said Campbell Danesh had taken him “under his wing” during their time on the show and had been “like a big brother, always looking out for me”.
“I will miss our chats. He was one of the most beautiful, intelligent and gentle souls I was lucky enough to know, a soul that lit up every room,” he said in his own tribute.
They were joined by Talent show titan Simon Cowell, actor Gerard Butler singer Paul Potts among others.