Los Angeles coroner's office has ruled that Whitney died from drowning in a hotel bathtub. However, officials said that heart disease and chronic cocaine use were contributing factors to the singer's death.
The autopsy findings end weeks of speculation about what killed her on 11 February, on the eve of America's Grammy awards.
Houston was found submerged in the bathtub of her room at the Beverly Hilton Hotel and her death has been ruled as accidental. Several bottles of prescription medications were found in her hotel room, but coroner's officials said they were not in excessive quantities.
"We are saddened to learn of the toxicology results, although we are glad to now have closure," Patricia Houston, the singer's sister-in-law and manager, wrote in a statement to the Associated Press.
Beverly Hills police said in a statement there was no evidence of wrongdoing in connection with Houston's death.
Craig Harvey, of the coroner's office, said cocaine and its byproducts were found in Houston's system, and the drug was listed as a contributing factor in her death. He said the results indicated Houston was a chronic cocaine user.
Toxicology results also showed Houston had marijuana, Xanax, the muscle relaxant Flexeril, and the allergy medication Benadryl in her system.
The singer also had a heart disease that caused blockages in her arteries.
Assistant chief coroner Ed Winter said the condition is common in drug users, although he said it was not clear whether Houston had a heart attack on the day she died. "It just beats up their heart," he said.
The exact amount of cocaine in Houston's system was not disclosed but will be contained in a full autopsy report to be released in about two weeks, officials said.