"The manner of death was certified as an accident", it added.
Miller was discovered unconscious in his home on September 7 and was pronounced dead at 11:51 a.m. after emergency crews arrived.
According to the report Mac died from "mixed drug toxicity" with fentanyl, cocaine and alcohol found in his system.
Unfortunately, McCormick struggled with staying sober, frequently slipping into excessive substance abuse.
As most know, the opiate epidemic has only gotten worse over the years, following the release of the opioid treatment, OxyContin, which users have gotten addicted to, and supplemented with other drugs such as fentanyl.
Close to Mac's body was an empty alcohol bottle on a nightstand, and he had a rolled $20 bill with white powder residue in his right pocket.
Miller's assistant arrived at the rapper's home that morning and discovered him unresponsive and kneeling beside his bed in a "praying position", the report stated.
The report described the substances found in Miller's apartment at the time of his death.
An unnamed insider told People "this is such a shock".
The Pittsburgh native and one-time partner of pop-star Ariana Grande had released his latest album "Swimming" days before his death and had been set to embark on a new tour.
Over the weekend, Grande dropped her new single, "Thank U, Next," in which she sang about her exes. Just last week, a tribute concert called "A celebration of life" was held to remember the artist with funds being raised for the newly founded Mac Miller Cirles Fund. Travis Scott, Chance The Rapper, Vince Staples and John Mayer were just some of the artisits who took to the stage in his honour.