The unidentified man was with two companions on Camelback Mountain Monday afternoon when they were set upon by the angry insects and had to run for safety.
"You're running. You're not thinking about what you're doing ... except you want to get out of there," witness Bree Wolfe told KSAZ-TV, Phoenix.
The victim apparently did not see the cliff as he ran and was killed instantly when he fell 150 feet.
The two other hikers were able to find some shelter in a tiny crevasse but were stung more than 300 times. A Phoenix firefighter wearing a bee suit was lowered by helicopter to help the pair. They were taken to a hospital in serious condition.
"Without the use of the helicopter for speed of rescue, there is a good chance there would have been three fatalities today," fire Capt. Scott McDonald said.
The names of the victims were not released. KTVK-TV, Phoenix, reported they were young men ages 18 to 20.