"Honestly, I hated it," the Grammy Award-winning singer admitted.
Mariah served as a judge for one season on the show, alongside Nicki Minaj, Randy Jackson and Keith Urban. She famously clashed with Nicki on a number of occasions.
"Here's what it was," Mariah confessed, during an interview with Hot 97's Angie Martinez. "I was the first person who signed on… I thought it was going to be a three-person panel.
"They gave me a nice… monetary moment, and I was just like, 'Ok, Randy Jackson will be there; I've known him forever. He used to play bass for me. Like, this isn't a big deal. This will be nothing.
"But it wasn't like that," she continued. "It was like going to work every day in hell with Satan."
Laughing, she added, "I'm just playing. It didn't affect me that much. I was disappointed."
While Mariah didn't specify which of her fellow judges she was referring too, her feud with Nicki was no secret.
The two got into very heated debates during the audition process, and occasionally took their altercations online — in May, rapper Nicki called Mariah "insecure" and "bitter" on Twitter.
There was one thing that Mariah really did enjoy. "You know what I loved? I loved the contestants," she said. "And some of them were so good — and also really good people, you could tell.
"It was disappointing when (the judges) would, for political reasons, not put people through."
Mariah is now back to doing what she loves. The mum-of-two is currently working on an album, due out at the beginning of 2014, and has just released a new single, The Art of Letting Go.
Neither she nor Nicki will return to American Idol for season 13 next year.