Young's family confirmed his death in a statement on Friday, saying he had a short battle with pancreatic cancer.
"Johnny was the creator, host and producer of the much-loved television show Young Talent Time," the statement said.
"He wrote and produced many iconic hit songs, including The Real Thing and Smiley.
"Johnny leaves behind his wife Marisha, sister Cornelia, daughters Anna and Fleur, son Craig (dec.), seven grandchildren, and two great-grandchildren.
"The family respectfully asks for privacy during this difficult time. Details of a memorial service will be announced soon."
The presenter was a fixture on Australian television screens with his much-loved program, which ran from 1971 to 1988 in its original run.
The show introduced now-famous Tina Arena, Dannii Minogue, Jamie Redfern and Debra Byrne to the public among its 40 cast members.
But the success of Young Talent Time had the effect of obscuring Young's own significant contribution as a recording artist.
Most notably, as a songwriter, he wrote The Real Thing for his friend Ronnie Burns in 1968 - until producer Ian "Molly" Meldrum heard it and insisted Young give it to his client Russell Morris instead.
The seven-minute psychedelic epic, written as a reaction to a Coca-Cola jingle, became an Australian standard, added to the National Film and Sound Archive's Sounds of Australia registry in 2013.
Young was born in the Netherlands as Johnny Benjamin Arthur de Jong on March 12 1947 before moving to Australia as a child and launching his pop career.
By the age of 18, he was already hosting his own television show in Perth, Club Seventeen, while putting together his own bands, Johnny Young and the Strangers and Johnny Young and Kompany.
With Kompany, he toured with the Easybeats in 1966. After splitting as a solo artist the following year, he supported the Rolling Stones, Roy Orbison, the Walker Brothers and the Yardbirds.
His biggest hit was a cover of the Beatles' All My Loving, which reached No. 4 nationally.
A self-penned song, The Star, was a hit for Ross D Wyllie before being covered by Herman's Hermits as Here Comes the Star.
In the meantime, his television career continued to flourish.
He began hosting The Go!! Show in 1967 after the resignation of future game-show compere Ian Turpie, winning his first Logie award as Best Teenage Personality.
When the show was axed, he moved to London, sharing an apartment with the Bee Gees' Barry Gibb, who encouraged him in his songwriting.
After returning to Australia, he concentrated on writing for other singers.
Smiley, written for Burns, was about their friend Normie Rowe's conscription for the Vietnam War.
Another song, I Thank You, was a No. 1 hit for boxer Lionel Rose in March 1970.
Young was inducted into the TV Week Logies Hall of Fame and the ARIA Hall of Fame during his lengthy career - the first artist to be inducted into both.
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