The feuding ex-friends will not return for a fourth season, even though the network had picked up the options on their contracts.
Fox said its midseason schedule didn't have a time slot for the show.
"We did not see a place for `The Simple Life' on our schedule this season," the network said in a statement.
However, 20th Century Fox Television, the studio that produces the show, hopes "The Simple Life" will move to another network — with Hilton and Richie.
"We're disappointed that `The Simple Life' will not continue on Fox where it has performed so well, but we believe this series ... is still a dynamic and valuable franchise," the studio said in a statement. "We hope to be able to announce a new network partner in the coming days."
Bunim-Murray Productions, which produces the show with 20th Century Fox, also released a hopeful statement: "We're very excited about the creative plans for the next group of episodes, and are confident this situation will be remedied quickly."
Us Weekly first reported the show's cancellation. When reached for comment, Hilton didn't sound as though she expected the show to return.
"I'm really excited about my movie projects, my new album and all my various other business ventures," she told the magazine.
The fish-out-of-bottled-water show started in 2003 with Hilton and Richie — both accustomed to plush lifestyles — spending the spring in the town of Altus, Ark., doing farm chores and working at the local dairy and gas station.
The series continued for two more seasons, including an "intern" edition in the business world.
But in April, Hilton issued a terse statement saying it was "no big secret that Nicole and I are no longer friends. Nicole knows what she did, and that's all I'm ever going to say about it."
The hotel heiress has given no reason for the split. She lobbied for Richie to be replaced by Rod Stewart's 26-year-old daughter, Kimberly, but Fox dismissed that option.
Richie, the 24-year-old daughter of Lionel Richie, became engaged to club DJ Adam Goldstein in February. Hilton, 24, earlier this month called off her engagement to Greek shipping heir Paris Latsis.