"Even though it looked like every other talk show -- it wasn't," the 47-year-old late-night host said during his monologue. "It was totally original, primarily because of the host of the show -- who, a lot of times -- seemed embarrassed to be there."
Kimmel revealed that he began "drawing pictures of Dave on the covers of all my textbooks at school." He even had a Late Night With David Letterman-themed birthday cake when he turned 16, as well as a Letterman letterman jacket and license plate that said "L&NITE."
Kimmel’s adoration for beloved host was boundless.
"We had no VCR, so I would have David Letterman viewing parties at my house in the middle of the night," he shared. "My friends who also loved the show would come over… at midnight and we would drink soda and watch the show. Looking back, I figured out why none of the girls at school wanted to have sex with me."
Kimmel admitted college was a waste ("I learned almost nothing") for him, but it was Letterman's Late Night that proved to be his course to life -- and eventually lead him to his own late-night career.
"Not only did I learn how to do everything from Dave," Kimmel said, "the reason I have this show is because the executives at ABC saw me when I was a guest on Dave's show -- and hired me to host this show. So I want to thank Dave and his writers and producers."
"I would like it if you would make sure to watch that instead of our show," he said of Letterman's final Late Show. "We will have a show on tomorrow night … but please do not watch it -- especially if you're a young person who doesn't understand what all the fuss is about."
Tearing up, he concluded, "Dave is the best and you should see him."
Kimmel wasn't the only late-night host to give a tip of the cap to Letterman. Jimmy Fallon also thanked Letterman on Monday’s Tonight Show.
"I, like every kid who grew up watching him, will miss him," Fallon said, before adding, "David Letterman is courageous. Have a nice retirement, Dave!"
On Tuesday, Late Night host Seth Meyers also redid the NBC show's credits to look like Letterman's when he was host of the Late Night.
Conan O’Brien, who will be the longest tenured late-night host once Letterman signs off, admitted to ET that he was "uncomfortable" with the 68-year-old leaving The Late Show.
"I don’t like it," he said of Letterman ending his TV reign. "He’s been there for 33 years, and it’s not going to feel good to me when he’s not on television."
ET revisited the top 10 moments with David Letterman. Press play in the video below to find out what made it!