Coroner Suzanne Greenaway said the soul diva died of accidental alcohol poisoning when she resumed drinking after weeks of being sober.
Greenaway said Winehouse was more than five times the British drunk driving limit when she died.
Pathologist Suhail Baithun said that blood and urine samples indicated that Winehouse had consumed a "very large quantity of alcohol" prior to her death. The level of alcohol in her blood was 416 milligrams per 100 milliliters, he said - a blood alcohol level of 0.4 percent.
The British and U.S. legal drunk-driving limit is 0.08 percent. Baithun said such high levels of alcohol intake could have stopped her breathing and sent her into a coma.
These findings come after an initial autopsy proved inconclusive.
The 27-year-old was found dead in bed at her London home on July 23.
Winehouse's doctor, Dr. Christina Romete, said the singer had resumed drinking in the days before her death. Prior to that, Winehouse had stayed away from alcohol for most of July, she said, although she had been swerving between abstinence and heavy alcohol use for a long time.
Winehouse had fought drug and alcohol problems for years.
The singer's parents attended the Wednesday hearing, but did not speak to reporters. In a statement, Winehouse family spokesman Chris Goodman said it was a relief to the family "to finally find out what happened to Amy."
Winehouse's breakthrough "Back to Black" album, released in 2006, was recently certified as the best-selling disc in Britain so far during the 21st century. The updated take on old-time soul also earned five Grammy Awards.
The Associated Press contributed to this report.