The ABC host is the cover boy of the new issue of Rolling Stone. The New York Daily News, which obtained an advance copy of the issue, reported that Kimmel said of Leno, "As a comedian, you can't not have disdain for what he's done: He totally sold out."
Kimmel, who moves his show from midnight to the 11:35 p.m. ET slot next week, said the NBC "Tonight Show" host "was a master chef who opened a Burger King."
Kimmel has voiced his negative feelings for Leno a few times in recent years. In 2010, he impersonated Leno on his program, and he also made an appearance on Leno's now-defunct primetime talk show, chastising him for planning a return to "The Tonight Show" after Conan O'Brien was forced out. And last year, at a New York City event, Kimmel said of Leno, "F*** him."
In his Rolling Stone interview, Kimmel is more complimentary of Letterman, his childhood idol.
"If I beat David Letterman in the ratings, does that mean I'm better than Letterman? No f***ing way," he said.
Kimmel also had nice things to say about Leno's NBC late-night colleague, Jimmy Fallon.
"People are going to compare me and him for years to come - we're being positioned as the Leno and Letterman of the next round," he said. "I like it because he's a very worthy competitor."
The issue of Rolling Stone featuring Kimmel hits newsstands Friday.