Cory Monteith died of an overdose of heroin and alcohol, a coroner has ruled.
The British Columbia coroner's office said that "there is no evidence to suggest the star's death was anything other than a most tragic accident".
The 31-year-old star of hit TV show Glee was found dead in his Vancouver, British Columbia, hotel room on Saturday. He was believed to be alone when he died.
Meanwhile Cory's girlfriend and co-star Lea Michele has thanked fans for their support in a new statement, obtained by People, saying she was grieving with the actor's family.
"Lea is deeply grateful for all the love and support she's received from family, friends, and fans. Since Cory's passing, Lea has been grieving alongside his family and making appropriate arrangements with them," read the statement.
"They are supporting each other as they endure this profound loss together. We continue to ask the media to respect the privacy of Lea and Cory's family."
Cory had talked bluntly about struggling with addiction since he was a teenager, calling it a serious problem and telling Parade magazine in 2011 he was "lucky to be alive".
Police said the actor had been out with people earlier, but video and electronic records from the hotel indicated he returned to his room by himself early on Saturday.
Cory admitted himself to a treatment facility in April for substance addiction, a representative said at the time. He also received treatment when he was 19.
Glee, with its catchy song-and-dance numbers and high-profile guest stars such as Gwyneth Paltrow and Britney Spears, became an instant hit when it debuted in 2009. Cory served as the show's resident hunk with a heart of gold.
The Fox network and the producers of Glee, including 20th Century Fox Television, have called Monteith an exceptional performer "and an even more exceptional person".
Gia Milani, who recently produced and directed a Canadian film featuring Cory, this week said he "seemed healthy" when she last saw him four weeks ago in Los Angeles. "He looked super fit and he was energetic and excited," Milani said. She said Cory showed no signs of a substance abuse problem while shooting the film a year ago.