Durham made her first recording at 19 and later achieved worldwide fame as lead singer of The Seekers after joining the group in 1963.
The group of four became the first Australian band to achieve major chart and sales success in the United Kingdom and United States, eventually selling 50 million records.
Durham embarked on a solo career in 1968 but recorded with The Seekers again in the 1990s.
In 2015, she was honoured as Victorian of the Year.
Durham passed away in a palliative care facility on Friday night, Seven Network reported on Saturday, citing a statement from Durham's management.
Tributes flowed for the beloved singer, with Prime Minister Anthony Albanese hailing Durham as "a national treasure and an Australian icon".
"Judith Durham gave voice to a new strand of our identity and helped blaze a trail for a new generation of Aussie artists," Mr Albanese said on Twitter on Saturday night.
"Her kindness will be missed by many, the anthems she gave to our nation will never be forgotten."
Opposition Leader Peter Dutton paid tribute to Durham as someone who "gave voice to more than one generation of Australians through words of universal appeal, carried by melodies that, once heard, became fixed in our memories".
"Durham demonstrated in song after song, concert after concert, how the human voice can reach, and move, every one of us," Mr Dutton said in a statement.
"Her language was uniquely Australian, and her voice a gift of universal beauty."
Victorian Premier Dan Andrews said the Essendon-born musician "went on to conquer the music world both here in Australia and overseas".
"With her unique voice and stage presence leading The Seekers, the band became one of Australia's biggest chart toppers," Mr Andrews said on Twitter.