Durham died in Melbourne on Friday night after suffering complications from a long-standing lung disease, her management said.
She 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 palliative care on Friday night after a brief stay in Alfred Hospital in Melbourne, Universal Music Australia and Musicoast said in a statement on Saturday.
Her death was a result of complications from a long-standing chronic lung disease, according to the statement.
The Seekers management team member Graham Simpson said: "This is a sad day for Judith's family, her fellow Seekers, the staff of Musicoast, the music industry and fans worldwide, and all of us who have been part of Judith's life for so long."
Durham's sister Beverley Sheehan spoke of the pair's shared love of music.
"Judith's joy for life, her constant optimism, creativity and generosity of spirit were always an inspiration to me," Ms Sheehan said.
Her bandmates in The Seekers -- Keith Potger, Bruce Woodley and Athol Guy -- said their lives had been changed forever by losing "our treasured lifelong friend and shining star".
"Her struggle was intense and heroic, never complaining of her destiny and fully accepting its conclusion. Her magnificent musical legacy Keith, Bruce and I are so blessed to share," they said.
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.
"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.
Australia's entertainment industry also responded to the sad news, with singer Anthony Callea posting: "the skies above just gained a voice of an angel."
Actor Magda Szubanski sent her "deepest condolences to her loved ones".
"Her beautiful, crystalline voice was the naive but knowing siren song of my childhood," Ms Szubanski tweeted.
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