The comic replaced Paula Abdul as a judge for a single season in 2010 and admitted that she found her time on the show "really hard".
DeGeneres has opened up about American Idol once again by revealing that she was discouraged by some of the contestants' attitudes.
She told Parade: "It was disappointing to hear things about the kids, the drama going on. Some of them are not as grateful as you would expect.
"All of a sudden they have fan mail, millions of people saying they're great, and some of them just stop appreciating it."
DeGeneres previously revealed that she found it difficult to criticise the contestants because she didn't want to damage their confidence.
"It was hard for me to judge people and sometimes hurt their feelings," she said.
Jennifer Lopez, Randy Jackson and Steven Tyler will return to judge the 11th season of American Idol, which premieres on Sunday, January 22 following the NFC Championship Playoff Game on Fox.
> Jennifer Lopez: 'I'm tougher now on American Idol'
> American Idol's Lauren Alaina on success: 'I've had to grow up'
Watch the American Idol season 11 promo below: