Carey tweeted that Cannon, 31, is suffering from "mild kidney failure." His representative confirmed Cannon's hospitalization in Aspen, Colo., where he and Carey were vacationing.
Carey posted a picture on her website of Cannon in a hospital bed as she lay beside him.
She asked for prayers and said Cannon's situation was "very painful." She later called it a "serious moment that's very tough on all of us."
The two became parents of twins, a boy and a girl, last year.
Cannon's representative had no further information Wednesday about his condition, but said he is still hospitalized.
The Associated Press contributed to this report.
