Bannister, 33, who won gold at the 2010 Delhi Commonwealth Games and was the national javelin record holder, had been training and living in Europe with his girlfriend.
Reports said there were no suspicious circumstances surrounding his death.
Bannister made the final of the world championships in Daegu, South Korea, and the Beijing Olympics.
The news shattered the Australian track and field community, in which the charismatic Bannister was a popular team member.
"RIP Jarrod Bannister. A talented athlete with so much more to give. You will be missed," Australia's dual world and Olympic hurdles champion Sally Pearson said on social media.
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"On behalf of Athletics Australia, I extend our deepest condolences to Jarrod's family and friends and urge the athletics fraternity to support each other at this difficult time," said chief executive Darren Gocher.
Bannister in 2013 was controversially banned for 20 months for missing drug tests.
The national record holder missed three tests within 18 months, which is treated the same as a positive test.
Bannister blamed poor communication and procedures by Athletics Australia as a factor behind the circumstances that saw him breach the ASADA Athlete Whereabouts programme, which requires the drug agencies to be informed of the movements of athletes at all times.
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