Kemp made his 10th and final out on his next swing and bowed out.
"It's hard," said Rockies outfielder Carlos Gonzalez, who was eliminated after four first-round home runs. "It's harder than people think. There's a lot of feeling and a lot of excitement. Sometimes you're trying to do too much and things don't go the way you want them to. I'm sure he can hit a lot more homers than just one. It didn't happen tonight. As a player, you don't want it to happen to you, but it did. All we're trying to do is trying to put on a good show for the fans."
Prince Fielder, the Tigers' big slugger, won the event.
Last year, Kemp hit two homers in a first-round exit.
In a tweet, Kemp wrote, "Wow!!!!! I went from 2 to 1!!!! Maybe I will hit 0 next year!!"
However, this time, there were extenuating circumstances. Kemp, who has been nursing a left hamstring injury, last played in a Major League game on May 30.
He won't play in Tuesday night's All-Star Game but should be activated as soon as the Dodgers open the second half on Friday night against the Padres.
Kemp, with Dodgers bullpen catcher Rob Flippo throwing to him, never looked in rhythm in Monday's Derby. He started with a grounder to short, then ripped a liner to center and a popup to first. Then, Kemp finally came close, hitting one off the wall in left. After that, there were two liners to left, a foul ball down the line in left and a grounder to third, leaving Kemp one swing from elimination.
Kemp stepped out, gathered himself and put one over the wall in center.
Swinging for the fence wasn't Kemp's only duty in the Derby. He also served as the captain for the National League, which also featured Gonzalez, the Cardinals' Carlos Beltran and the Pirates' Andrew McCutchen.
In fact, Kemp fared better than American League captain Robinson Cano, the defending Derby champion who was shut out this year.