Taking effect in the third most populous U.S. state, the law escalates a Republican political strategy to pursue bills restricting transgender rights. More than 500 bills affecting LGBTQ matters have been proposed across the country and at least 48 have been enacted, according to the Human Rights Campaign.

Such bills were once mostly limited to regulating changing rooms and women's sports but have expanded to limiting healthcare access even for transgender adults. In some cases legislation has sought to charge parents and doctors with child abuse if they provide treatment to transgender youth.

"This will permanently outlaw the mutilation of minors," DeSantis said at a bill-signing ceremony in Tampa.

"I mean they're trying to do sex change operations on minors, giving them puberty blockers and doing things that are irreversible to them," the Republican governor said.

Surgery for minors is exceedingly rare and only occurs after extensive monitoring by multiple medical professionals.

A group of parents of transgender children immediately challenged the law, filing an emergency request in federal court to block its implementation.

DeSantis, who is expected to launch a bid for the 2024 Republican presidential nomination next week, has staked part of his political future on cultural issues surrounding LGBTQ rights.

In addition to Florida, at least 14 other states have banned treatments for transgender youth, although many face legal challenges in the courts.

Many Republican supporters of the bills distrust the prevailing medical consensus, which endorses gender-affirming care and in some cases considers it life-saving. Instead, opponents of transgender healthcare claim it is dangerous and experimental, with some labeling the measures as chemical castration or child abuse.

The World Professional Association for Transgender Health (WPATH) criticized passage of the bill, saying it interfered with the doctor-patient relationship.

"Florida's bill has created a chilling effect on the medical community by inserting politics into health care," Marci Bowers, the association's president, said in a statement.

The Florida law, known as Senate Bill 254, requires transgender adults to obtain written consent on a form adopted by the Board of Medicine and Board of Osteopathic Medicine - two oversight boards whose members are appointed by the governor and have already taken steps to restrict transgender care under DeSantis.

In addition, the new law, which takes effect immediately, grants state courts jurisdiction in child custody battles over transgender minors when a Florida parent opposes treatment that is being pursued under an out-of-state parent.

DeSantis also signed into law a so-called "bathroom bill" requiring all restrooms or locker rooms at public facilities to be used exclusively for people based on their gender assigned at birth.