The boy, 17, was found with severe leg injuries after being bitten while surfing in Wooli Bay in New South Wales, about four hours' drive from Brisbane.
He died at the scene despite paramedics' efforts to revive him.
Local lifeguards described the boy's death as "a very tragic accident."
A Surf Life Saving NSW spokewoman told ABC: "We've had numerous incidents, and some fatal, on the mid-north coast and north coast over the years, it is a bit of a shark hotspot."
Beach and emergency service workers will now try to find the shark, she said.
The spokeswoman added: "We will hope to get a jet ski to get on the water with one of our volunteers tomorrow.
"But we are conscious it's in a really remote spot; it's 15 kilometres from the main highway to get to Wooli and this part of the coast is in a national park camping ground."
Police said local beaches were closed in the aftermath of the attack. An investigation into the boy's death is ongoing.