Police were called to a Cable Beach in the morning after reports of the attack.
The man was pulled from the water and given medical treatment but later succumbed to his injuries.
"Police can confirm that tragically the man has died," Western Australia police said in a statement.
Shark attacks are rare on Cable Beach, a 22-kilometre stretch of pristine white sand next to the town of Broome.
But authorities are generally forced to close the beach once or twice a year when deadly saltwater crocodiles are spotted nearby.
The man's death marks the eighth fatal shark attack in Australian waters this year.
There have been at least 22 shark maulings in the same period, according to the Taronga Conservation Society Australia government agency.