Coroner's office spokesman Ed Winter says the 41-year-old rocker hanged himself from a bedroom door in his home near Los Angeles, reported Variety.
Bennington was found dead on Thursday.
Winter says a half-empty bottle of alcohol was found in the room, but no drugs were evident. Bennington struggled with drug and alcohol addictions at various times during his life.
A suicide note was not found. An autopsy has not yet been scheduled.
Bennington also appeared to be deeply impacted by the loss of Soundgarden singer Chris Cornell, who died in May and was good friends with Bennington. The Linkin Park frontman died on what would have been Cornell's 53rd birthday.