The 'We Belong Together' singer officially signed on for Idol last week after reportedly agreeing to a $17m salary.
Host Seacrest discussed how Carey will change the Fox show's dynamic in a new interview with The Hollywood Reporter.
"I think that Mariah will fit right in. She knows the rhythms of this kind of thing," he said.
Seacrest also discussed how Carey will compare to Jennifer Lopez, who has exited American Idol after two seasons.
"Jennifer had watched a lot of Idol; I'm not sure how much Mariah has watched," he explained.
"Certainly, she's watched less of the show, which I think is fine. She's pretty open, and she doesn't sugarcoat much, at least in my experience with her."
Brad Paisley has also been linked to the judging panel. Nick Jonas and Pharrell Williams are apparently being considered as well.
Snoop Dogg expressed an interest in judging American Idol on Thursday (August 2), vowing to clean up his act if he is hired.
American Idol returns to Fox in 2013, with open auditions currently under way across the US.
