Charlotte Lindström, 23, who was a regular in the social pages of Sydney's newspapers, had pleaded guilty and agreed to give evidence against others involved in the case.
She was accused of offering AU$200,000 dollars (US$185,000) to an undercover policeman to kill two men who were scheduled to give evidence against her boyfriend Steven Spaliviero.
In one conversation, she told him Spaliviero wanted the two witnesses "in a cemetery" rather than a hospital, the court heard.
Lindström, who had apologized in court for her actions and said she wished she could "turn back time," wiped away tears as she was sentenced, the national AAP news agency reported.
Judge Steven Rothman said she would spend the rest of her life "looking over her shoulders" after the assistance she had given to authorities in the face of death threats.
He referred to psychological reports which said Lindström suffered from anorexia and had romanticized her relationship with her boyfriend.
"She presents as emaciated, chronologically young and emotionally immature," Rothman said, noting that she had been moved to solitary confinement after threats were made against her in prison.
Lindström was sentenced to three years and 10 months in jail but as she has been in custody awaiting trial since May last year she will be eligible for release on parole in May next year.