The legislation, which takes effect 90 days after the Legislature adjourns in May, makes performing an abortion punishable by up to 10 years in prison with a fine of $100,000.
Senate Bill 612 does not authorize criminal charges against a woman for receiving an abortion and makes an exception only for an abortion performed to save the life of the mother.
"We want to outlaw abortion in the state of Oklahoma," Stitt said during a signing ceremony for the bill. "I promised Oklahomans that I would sign every pro-life bill that hits my desk, and that’s what we’re doing here today."
Sen. Nathan Dahm, a Broken Arrow Republican who wrote the bill and is running for Congress, called it the "strongest pro-life legislation in the country right now, which effectively eliminates abortion in Oklahoma."
Dahm promised his Twitter followers on Sunday to do "everything in [his] power to end abortion on the national level" and hit back at Vice President Kamala Harris, who had called the bill "shameful" and said it would "only prevent women from getting the health care they need."
"Our bill is not an attack on women's reproductive rights, because women do not have the right to terminate life due to an unwanted pregnancy," he said in a statement responding to the vice president.
"In Oklahoma, we don't take advice from corrupt establishment elites. Kamala Harris should focus on doing her job," Dahm said.
Stitt had pledged to sign any anti-abortion bill the legislature would send to his desk.
This move follows a trend of Republican states passing restrictive abortion laws in the last few years and as the conservative U.S. Supreme Court considers ratcheting back abortion rights that have been in place for nearly 50 years.
Planned Parenthood’s abortion clinic in Oklahoma has seen an 800% increase in the number of women from Texas after that state passed its new anti-abortion law last year.
However, abortion rights advocates say the bill is unconstitutional and likely to face a legal challenge – like similar anti-abortion bills that have been approved in conservative states and stopped by the courts.
"OK’s Governor just signed a law that would make it *illegal* to get an abortion. This is unacceptable," Planned Parenthood Action tweeted Tuesday. "We are doing everything we can to stop this unconstitutional ban from going into effect."
"Abortion is NOT a crime. It is ESSENTIAL health care. The Center will challenge this unconstitutional law in court with @PPFA to protect abortion rights and access in #Oklahoma," the Center for Reproductive Rights wrote.
Nevertheless, the Supreme Court's decision to allow Texas abortion restrictions to remain in place has buoyed anti-abortion lawmakers.
All of this comes as the country waits for the Supreme Court's decision on Dobbs v. Jackson Women’s Health Organization, which is a challenge to the landmark Roe v. Wade decision.
Fox News' Brie Stimson and The Associated Press contributed to this report.