The 41-year-old was found dead in his home in Palos Verdes near Los Angeles shortly before 9am on Thursday.
A Los Angeles County coroner confirmed they were investigating Bennington's death as an apparent suicide but no additional details were available.
Law enforcement officials say Bennington hanged himself in his bedroom and he was home alone at the time, according to TMZ. He was found upstairs by his housekeeper.
'Chester was one of the brightest and most talented people on this planet, and he lived life to the fullest,' a close friend told RadarOnline, adding that the Bennington suffered from demons.
Bennington's suicide came on the day of his late lifelong friend Chris Cornell's birthday. The Soundgarden rocker killed himself in May by hanging. Cornell would have turned 53.
'Chester and Chris were so close, and he was never the same after Chris’s death,' the friend told Radar.
The friend of Bennington's also noted that Cornell's death deeply affected Bennington, who also struggled with 'addiction issues'.
'But everyone thought that he had it licked. He seemed to be at a good place in his life. It is just so tragic and there are no words,' the friend told Radar.