New laws before the Victorian parliament will outlaw therapy that attempts to change or suppress a person's sexual orientation or gender identity.
Attorney-General Jill Hennessy on Wednesday described the practice of gay conversion therapy as "bigoted quackery".
"Our government is very firmly of the view that gay, lesbian and trans people, they don't need to be fixed, they are perfect the way they are," she told reporters outside parliament.
"What we won't stand by is to have services, whether they're therapeutic health services or pretending to be, or religious techniques, imposing on people something I think is the height of cruelty."
Ms Hennessy said Victorians had been starved, tortured, told to "pray the gay away" and even married off young in an effort to suppress their sexuality or gender identity.
"Some of the stories involved what I would call forms of criminal assault," she said.
The Change or Suppression (Conversion) Practices Prohibition Bill, to be introduced to the Legislative Assembly on Wednesday, denounces such practices as deceptive and harmful.
The bill will empower the Victorian Equal Opportunity and Human Rights Commission to investigate reports of conversion practices.
It also puts in place strong criminal sanctions for people who subject others to conversion practices that cause injury or serious injury - with up to 10 years' jail for the latter.
Those who try to get around the laws by sending people to conversion practices out of the state would also face criminal sanctions and fines to a maximum of almost $10,000.
In August, Queensland became the first state to criminalise gay conversion therapy, with the ACT following suit a week later.
Due to the limited remaining sitting weeks in 2020, it's unlikely the legislation in Victoria will pass until 2021.
Australian Associated Press