The fish, believed to be a bull shark, bit Billy O'Leary twice, slicing his flesh down to the bone and severely damaging his Achilles tendon.
Mr O'Leary, 20, managed to get himself ashore at Nobbys Beach where friends bound the wound to stem the bleeding.
"There were two bites. One is sort of half in his calf, that's taken a big chunk out of that," fellow surfer Tim Windisch told the Gold Coast Bulletin newspaper.
"The other one is down to his heel. It's just right down to the bone. You could see the bone."
Chief lifeguard Warren Young said it appeared Mr O'Leary landed on the bull shark, an aggressive species known for its tendency to attack humans.
"He feels like he perhaps landed on it - he's come off his board and landed on it doing an aerial," Mr Young said.
"That's what he's said to us, so maybe he's landed on it and it's reacted. Read More