Lopez confirmed her rumored departure Friday on "Idol" host Ryan Seacrest's KIIS-FM, Los Angeles, morning show.
The announcement came a day after co-star Steven Tyler said he also would not be back for a third season as judge.
"I honestly feel like the time has come that I have to get back to doing the other things that I do, that I put ... on hold because I love 'Idol' so much," Lopez said.
"I could do 'Idol' for the rest of my life," she said. "But that would be giving up a bunch of other things. We had an amazing run. ... I have my movies and my music and my this and my that ...
"It all kind of worked together for a while, but then it gets more complicated. As the kids are getting a little bigger, it started feeling like it was a lot. Something has to give. And that's, I think, where I am right now."