The camper was inside his tent Friday night when a black bear clawed through the tent and scratched the man's head, giving him serious lacerations. Sheriff's officials said the bear appeared to be attempting to get into the tent.
The camper suffered a severe cut to the top and back of his head, requiring two dozen stitches. He is expected to make a full recovery.
Fellow campers in the area told officials they saw a bear in the area near the time of the attack.
Department of Fish and Wildlife officials said it is their policy to track down and euthanize a bear if it attacks a person.
Officials caught a bear they believed to be responsible and performed a DNA test to see if they had the right animal.
After wildlife officials confirmed the test came back positive, the bear was put down.
"Once there's an attack, we have to err on the side of caution and assume that bear has been conditioned or maybe has lost that fear of humans," said Lt. J.C. Healy with the Department of Fish and Wildlife.
Authorities said the camper did not have anything in the tent that would have attracted the bear, like food or toiletries.
Healy said this type of attack is very rare and called it "a statistical anomaly."
"The California black bear, very docile, very skittish, doesn't want anything to do with human interactions," Healy said.
Millard Canyon was shut down but was reopened on Wednesday.