Greg Pickering, 55, was diving for sea snails off an area called Poison Creek near the Western Australia city of Esperance when he was attacked by what officials suspect was a great white.
He underwent surgery and was in a stable condition, Royal Perth Hospital spokesman Matt Avery said.
In 2004, Mr Pickering was bitten on the leg while spearfishing near Cervantes, north of the Western Australia capital, Perth.
In an interview from his hospital bed following that attack, the long-time diver told Australia's Ten News that the incident would not stop him from getting back in the water.
"One incident has happened in 34 years," he said at the time. "I'd say that's very small odds."
Mr Pickering suffered injuries to his head and face in the latest attack, Royal Flying Doctor Service spokeswoman Carrie Parsons said. He was flown from a hospital in Esperance to the Perth hospital for surgery.
Officials from the Department of Fisheries are scouring the waters off Poison Creek trying to catch and kill the shark.
Sharks are common in Australian waters, though the nation has averaged just more than one fatal attack per year over the past 50 years.