DeWine's signature makes OH the fifth state to ban abortions after the first detectable fetal heartbeat.
"The essential function of government is to protect the most vulnerable among us, those who don't have a voice", DeWine said as he signed the bill.
State Rep. Christina Hagan, a Republican who sponsored the bill, previously told reporters that lawmakers drafted the legislation in direct opposition to Roe v. Wade: "Our intention is to go directly to the heart of Roe v. Wade and to challenge the question of when a life begins in the United States and when [unborn babies'] constitutional protection is due to them".
The new law makes it a fifth-degree felony offense in OH to induce or perform an abortion after the detection of a fetal heartbeat, except in a case of medical emergency.More news: Pope Francis kisses shoes of Sudanese leaders in plea for peace
"Heartbeat" bills have passed the legislature in Missouri, Ohio, and Tennessee and have been introduced in Florida, Illinois, Louisiana, Maryland, Minnesota, New York, Georgia, South Carolina, and West Virginia.
Even before the bill was signed, the American Civil Liberties Union of OH reportedly said it was preparing a suit to challenge to the law, something DeWine and OH pro-life advocates anticipated.
A transvaginal ultrasound scan can sometimes detect the foetal heartbeat as early as five weeks gestation, before most women even know they are pregnant.
But DeWine defended Ohio Republicans" decision to push the boundaries of the law, because "it is the right thing to do'.
The ACLU of OH promised to challenge the new law with a lawsuit, calling the ban unconstitutional.More news: Chinese scientists create monkeys with human brain genes
According to an analysis of the bill by the Ohio Legislative Service Commission, abortion providers are required to keep documention of a woman's medical issues for seven years.
In Georgia, where Kemp is expected to sign the heartbeat bill soon, more than 50 actors, including Alyssa Milano, Alec Baldwin and Amy Schumer, have threatened a campaign to pull Hollywood productions out of Georgia - a hub for TV and movie projects - if the ban is enacted.
"If this is what it takes, we will see you at the Supreme Court", said Planned Parenthood of Ohio President Iris Harvey at a rally Wednesday outside the Statehouse.
The Ohio Senate originally passed the bill last month.
Currently, Ohio prohibits abortions after 20 weeks of pregnancy, and lawmakers in 2018 passed a law banning the "dilation and evacuation" method of abortion used most commonly after 12 weeks of pregnancy. Additionally, the woman getting the abortion would be obligated to sign papers conceding she is allowing the abortion, and that "the unborn human individual that the pregnant woman is carrying has a fetal heartbeat and that the pregnant woman is aware of the statistical probability of bringing the unborn human individual that the pregnant woman is carrying to term".
(Fred Squillante/The Columbus Dispatch via AP) Gov. Mike DeWine signs a bill imposing one of the nation's toughest abortion restrictions, April 11, 2019 in Columbus, Ohio.More news: Jedi: Fallen Order Officially Revealed at Star Wars Celebration