Although the cause of death is not yet known, police have ruled out foul play.
The actor had checked into Fairmont Pacific Rim Hotel on July 6 and was scheduled to check out Saturday, according to police. When he did not check-out, staff went to his hotel room at noon and discovered his body.
"We are so saddened to confirm that the reports on the death of Cory Monteith are accurate. We are in shock and mourning this tragic loss," his rep said in a statement.
Monteith starred as Finn Hudson in Fox's music-themed comedy-drama hit since it began in 2009. His fellow cast member Mark Salling tweeted shortly after the confirmation, "no".
In April, his rep told ABC News that he had checked into rehab. In a 2011 interview with Parade magazine, Montieth said he got treatment at 19 for his addiction struggles that included taking "anything and everything." He told Parade that he was "lucky to be alive."
Police said they believe he was alone when he died. An autopsy is scheduled for Monday.