Ms Giuffre became the face of a legal battle against the disgraced financier when she said Epstein sexually abused her and arranged for her to have sexual encounters with men including Britain's Prince Andrew starting when she was 17.
King Charles' younger brother strenuously denied her allegations.
Her solicitor Karrie Louden confirmed on Saturday the mother-of-three had died at her farm in Western Australia.
"We're all in shock," she told AAP.
"She was absolutely inspirational."
Ms Louden said she was initially contacted by Ms Giuffre's carer and went to the property to confirm the news.
"It was an honour to work with someone who was so strong and powerful and willing to advocate for victims of sexual abuse.
"It's a devastating loss to the community and survivors all over the world who saw her as an inspiration."
Ms Giuffre's family on Saturday also issued a statement confirming she took her own life after "the toll of abuse" became too heavy.
"She lost her life to suicide, after being a lifelong victim of sexual abuse and sex trafficking," it read.
Ms Giuffre captured global attention in March when she shared a photo on social media showing her face with what appeared to be extensive bruising.
In the post, she said she had been involved in a bus crash, was hospitalised with kidney renal failure and had four days to live.
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