Carl Mock, 40, suffered a massive stroke and other severe injuries after being mauled near a campground just outside Yellowstone National Park.
Officials say that Mr Mock, who is from West Yellowstone, Montana, died at an Idaho Falls hospital on Sunday, several days after the attack.
Investigators and wildlife officials, including bear specialists, visited the area the day after Thursday’s attack to assess public safety.
Authorities say that as they made noise to move on any bears still in the area, they were charged by one of the animals.
The older male grizzly was shot and killed by the investigators and died within 20 yards of the group.
Further investigation found the moose carcass within 50 yards of the original attack site, and experts believe the bear had been defending the food source when Mr Mock was injured.
Experts say that attacks by grizzly bears are rare and that the animals tend to move away form humans if they hear them coming.