Prince died of a self-administered fentanyl overdose.
The 57-year-old musician's death was an accident caused by fentanyl toxicity, according to a report released by the Midwest Medical Examiner's Office, which carried out an autopsy on April 22, the day after he died.
Fentanyl is an opioid with a high risk for addiction and dependence and is used to treat severe pain.
A note on the report states that "the decedent self-administered fentanyl".
Prince, whose full name was Prince Rogers Nelson, was found unresponsive in an elevator at his Paisley Park home in Chanhassen, Minnesota.
The report was released after an unnamed law-enforcement official revealed that Prince's death was caused by an opioid overdose.
It was previously claimed that Prince had been addicted to the painkiller Percocet for years because of problems with his hips and that he had to be given a "save shot" almost a week before his passing after he overdosed on the highly-addictive drug, which contains acetaminophen and oxycodone
Prince - who had used a cane to help him get around for many years - had long needed a double hip replacement but reportedly turned it down on numerous occasions but he was worried it would require a blood transfusion, which would have conflicted with his beliefs as a Jehovah's Witness.
The singer was rushed to hospital in Moline, Illinois on April 15 for the shot, which is administered to counteract the effects of opiates, after being taken ill on his private jet on the way back from a gig in Atlanta.
However, Prince's bodyguard Chris Gaither previously slammed reports that the star was addicted to painkillers.
He said: "I packed this man's bag on the daily. I have been on tour with him for months. So if anybody had an addiction that would be something you would see. That would be something that you would know.
"He may have had an issue where he had to go to the doctor and they prescribed something for him, but as far as him abusing stuff, that's not him. When it comes to health, he's the fittest person. Only time doctors would come in, they would give him a B-12 shot, something like that, when he might have been feeling sick or low on energy. But other than that, he wasn't taking stuff. He had more energy than everybody just off his natural presence."