It is now illegal to get or provide nearly any abortion in Oklahoma.
Governor Kevin Stitt signed House Bill 4327 into law banning abortions from the moment of conception.
It makes Oklahoma the most restrictive state on abortions in the country.
Under the measure, anyone could sue someone in civil court who performs, aids or abets an abortion.
The exceptions are if the mother's life is in danger, or if the pregnancy is the result of rape or incest that was reported to law enforcement.
The bill also includes language attempting to prevent legal challenges to the legislation.
Governor Kevin Stitt issued a statement saying in part: "From the moment life begins at conception is when we have a responsibility as human beings to do everything we can to protect that baby's life and the life of the mother."
Emily Wales is the president and CEO of Planned Parenthood Great Plains.
She released a statement, saying in part: "Oklahoma's politicians, from the governor on down, are determined to strip rights from anyone who could become pregnant. This is no surprise in a state that has consistently ranked among the worst in the nation for maternal mortality and child health outcomes."
The law took effect immediately.