Josie Harris -- Floyd Mayweather's ex -- died from the result of an accidental overdose of Rx medication, TMZ Sports has learned.
We broke the story, Harris was found unresponsive in her car in front of her Valencia, Calif. family home back in March.
We were told despite lifesaving efforts from emergency personnel ... Harris passed away on the scene at 40 years old.
An autopsy was conducted, which included toxicology, and we're told the family has now been informed the official cause of death is listed as an accidental overdose.