Underwood, 29, has joined former Idol favourite Adam Lambert, Mariah Carey, will.I.Am and Fergie as potential replacements for Jennifer Lopez and Steven Tyler, who both quit the show last week.
Clarkson said that she has given her vote to 'Before He Cheats' hitmaker to the vacant judging role on the show where she first found fame.
"I don't want to be a judge. Mentor is more my style. And not just mentoring, getting to be a part of the song with them (contestants), getting them amped up.
"But (Underwood) she would. Didn't she major in journalism or something?" She can have that face... That bluff face! She can put that on! She would be good," Clarkson said.
