"The pen has run dry, its ink no longer flowing - yet Mr. Curly and his ducks will remain etched in our hearts, cherished and eternal," reads a statement posted on his Instagram account.
Leunig, as his cartoons and paintings were always signed during his six-decade career, died peacefully in the early hours of Thursday.
He was surrounded by his children and loved ones, as well as classical music and sunflowers, during his final days.
View this post on Instagram A post shared by Michael Leunig (@leunigstudio)
Michael Leunig was born in East Melbourne in June 1945, the second eldest of five children.
He went to Footscray North Primary School and Maribyrnong High School, and cited Enid Blyton, Phantom comics, JD Salinger, The Beatles and Spike Milligan as among his early influences.
As a young man, his growing political consciousness intensified in 1965 when he received a notice of military conscription during the Vietnam War.
However as he was born completely deaf in one ear, he was deemed not fit for service, and instead went to work as a labourer and meatworker before starting his career as a political cartoonist.
Since his first cartoon for The Age in 1969 he became popular and widely loved by the public, publishing his first collection in 1974 and another 23 collections since.
Leunig was also a painter, philosopher and poet, with many of his images accompanied by mischievous rhyming couplets.
But he was best known for his whimsical drawings of ducks and long-running character Mr Curly.
Leunig was a cartoonist for The Age newspaper from 1969 until August this year. (Julian Smith/AAP PHOTOS)
Leunig made many cartoons against war, corruption and grubby politics - and just as many that were for the cause of humanity, kindness, gardening, and nature.
Leunig was declared a national living treasure by the National Trust in 1999 and has been awarded honorary degrees from La Trobe, Griffith and the Australian Catholic University.
Some of his cartoons sparked controversy over the years, and Leunig was let go by Nine's publishing division in August.
Writing about the end of his tenure on his website, Leunig said he was "disposed of" along with many others in a cost-cutting "media bloodbath", and he was sad about what has become of newspapers.
"With some terrific exceptions, Australian mainstream cartoonists can't be so funny, spirited and naughty any more," he said.
Spectrum editor Lindy Percival paid tribute to Leunig's career when his final cartoon was published.
"Through Leunig's work, we have contemplated life's beautiful and occasionally baffling moments: Mr Curly arriving home to his curly-headed family; a simple soul dreaming of floating coloured petals; and a father and son watching the sun set on TV, oblivious to the real thing happening outside their window," she wrote.
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