The landscape painter passed away last month (Apr12) at his home in Monte Sereno, California.
Autopsy results showed Kinkade stopped breathing at the property after consuming Valium and alcohol, according to NBC Bay Area News.
The Santa Clara County medical officer also ruled ""hypertensive and atherosclerotic heart disease"" contributed to the tragedy.
Kinkade, one of America's most-collected artists, battled alcoholism during the final five years of his life following the breakdown of his marriage. He attempted to curb his drinking but struggled to quit altogether.
Following his death, his estranged wife Nanette Kinkade issued a statement which read, ""Thom provided a wonderful life for his family. We are shocked and saddened by his death.""