The star - who was also a well-known disability campaigner - had a genetic disorder known as steogenesis imperfecta, which causes bones to break easily, reported BBC online.
She passed away "unexpectedly" on Saturday (December 6). A private funeral will take place in the coming weeks, and will be followed by a public event in Melbourne.
Her family issued the following statement: "With great sadness we acknowledge the passing of Stella Young, our much-loved and irreplaceable daughter and sister.
"Stella passed away on Saturday evening, unexpectedly, but in no pain."
Former Prime Minister Julia Gillard paid tribute to Young, tweeting: "Stella Young was a shining light for care and action on disabilities. We mourn her passing and rededicate ourselves to her spirit.