The singer, who appeared on the TV talent show in 2014 and made it to the final six, died on Sunday after being rushed to hospital following an apparent heart attack in Alabama, IOL reports.
As first reported by TMZ, Harris was later pronounced dead, and the Walker County coroner has confirmed the news to multiple media outlets.
His cause of death is yet to be confirmed, but the coroner said it seemed “natural” while there is currently no evidence of foul play.
Harris participated in the 13th season of American Idol, and impressed judges Keith Urban, Jennifer Lopez and Harry Connick Jr with his audition.
Tributes have poured in for Harris following his death, with the official American Idol Twitter account hailing him as “an incredible talent”.
The post read: “CJ Harris was an incredible talent, and the news of his passing deeply saddens us. He will be truly missed.”
Caleb Johnson, who won the show in 2014, paid tribute to his friend.
“Life is so fragile! I am so grateful that our lives got to cross paths in this lifetime. You were a beautiful, kind soul that always made the room brighter with your smile and laughter.
“Love you brother, you were taken from us way to soon! Until we meet again RIP @cjharrismusic.”
Alex Preston wrote: “RIP CJ. I can’t believe this, I woke up and thought it was a dream. I love you dude. I’ll always remember the good times we all had.”
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