And Jimmy makes three.

Starting on Tuesday night, all three traditional broadcast networks will go head-to-head at 11:35 with entertainment-talk shows, as Jimmy Kimmel on ABC joins Jay Leno on NBC and David Letterman on CBS.

“Yes, I’m helping to further cheapen the medium,” Mr. Kimmel said in a telephone interview.

The truth is, Mr. Kimmel has worked doggedly for a decade to carve out his own identity in late night. And over the last several years, especially in 2012, Mr. Kimmel has begun to emerge as a well-respected, distinctive late-night star, one ABC finally deemed ready for the big stage, the show right after the late local newscasts.

The decision to move Mr. Kimmel from his midnight start time meant displacing the award-winning late-night news program “Nightline.” But ABC’s management has, since 2002, been seeking to switch to entertainment in late night, for the simple reason that the advertising money is so much greater for an entertainment show. ABC tried to woo both Mr. Letterman and Mr. Leno over that period, while Mr. Kimmel persevered, improving his monologue skills, polishing his performing style and making increasingly clever use of videos that stamped his show as an original rather than an imitation.