Greater the flamingo was put to sleep on Friday due to complications brought about by arthritis and old age, officials at Adelaide Zoo said.
The flamingo, named after its species, arrived at the zoo in 1933 and was a popular attraction.
Flamingos are wading birds with a very specialised diet. They have far shorter life spans in the wild.
Greater flamingos - scientific name Phoenicopterus roseus - are usually larger than lesser flamingos and are characterised by pale plumage and pink bills.
Greater the flamingo, who survived a bad beating by a group of teenagers in 2008, was a zoo favourite, officials said.
"Greater is best known for being the world's oldest flamingo and the last greater flamingo to have resided in Australia," Elaine Bensted, Zoos South Australia chief executive, told Agence-France Presse news agency.
"Although this is an extremely sad loss for us all, it was the right thing to do," she said, adding that there was no treatment that could have improved the flamingo's quality of life.
The flamingo is survived by companion Chilly the Chilean flamingo, 65, said to be the last flamingo in Australia.
Zoo officials said they would keep a close watch on Chilly to see if there was any reaction to Greater's death.
They were also considering a memorial for Greater, they said.
A flamingo believed to be the oldest of its kind in the world has died at the age of 83 in Australia.