Ray Lewis III -- the son of NFL legend Ray Lewis -- died from a lethal mix of drugs ... according to an autopsy report obtained by TMZ Sports.
In the medical examiner's documents, officials say fentanyl, cocaine and methamphetamine intoxication was what led to the former football player's son's passing.
They ruled the manner of death as accidental.
According to the toxicology report, Lewis III additionally had alcohol and alprazolam -- the drug found in brands like Xanax -- in his system at the time of his death.
We broke the story ... cops say after responding to a call for a medical emergency at a residence in Florida back on June 14 -- they discovered an unresponsive Lewis III.
They said at the time a friend had been screaming for Narcan (a drug used during overdoses) ... and when they eventually administered it in his right nostril, there was no response. Lewis III was later pronounced deceased.
He was just 28 years old.
Ray Lewis remembered his son fondly at the funeral days later, saying in an emotional speech, "We will see you again."