"I know I was supposed to do conan on wed, but there was a death in my family," Kris announced to his fans via his Twitter account.
Kris is mourning the loss of his grandmother, a rep for the "Idol" told Access Hollywood.
The Conway, Ark., singer, who is currently on "The American Idols Live Tour" with his former reality show competitors, said one of them – Allison Iraheta — will now take his slot on the late night television show.
Allison "is filling in," he Tweeted. "And by filling in I mean [Allison] is gonna rock Conan's face off on Wednesday."
And Kris' tour pals were quick to offer the singer their support over his loss.
"love ya man .. Keep yo head up," Allison Tweeted.
"I know kris appreciates all the concern-- keep his family in your thoughts," Anoop Desai wrote on his Twitter page.
Despite his loss, the singer's rep told Access that Kris would not be canceling any dates on the tour.
Related Content from AccessHollywood.com:
PLAY IT NOW: 'American Idols' Answer Fan Questions (June 2009)
PLAY IT NOW: Kris Allen Talks 'Idol' Win (May 21, 2009)