The conservative-dominated court overturned the landmark 1973 "Roe v. Wade" decision that enshrined a woman's right to an abortion, saying that individual states can now permit or restrict the procedure themselves.
"The Constitution does not confer a right to abortion," the court said. "The authority to regulate abortion is returned to the people and their elected representatives."
Hundreds of people -- some shedding tears of joy and others weeping with grief -- gathered outside the fenced-off Supreme Court, where security was tightened ahead of the ruling.
"It's hard to imagine living in a country that does not respect women as human beings and their right to control their bodies," said Jennifer Lockwood-Shabat, 49, a mother of two daughters who was choking back tears.
But Gwen Charles, a 21-year-old opponent of abortion, was jubilant.
"This is the day that we have been waiting for," she told AFP. "We get to usher in a new culture of life in the United States."
The Supreme Court ruling will likely set into motion a cavalcade of new laws in roughly half of the 50 US states that will severely restrict or outright ban and criminalize abortions, forcing women to travel long distances to states that still permit the procedure.
In the majority opinion, Justice Samuel Alito said Roe v. Wade was "egregiously wrong."
"Abortion presents a profound moral issue on which Americans hold sharply conflicting views," he said. "The Constitution does not prohibit the citizens of each State from regulating or prohibiting abortion."
The ruling represents a victory of 50 years of struggle against abortion by the religious right -- with campaigners now expected to keep pushing for an outright nationwide ban.
The court tossed out the legal argument in Roe v. Wade that women had the right to abortion based on the constitutional right to privacy over their own bodies.
Alito's opinion largely mirrors his draft opinion that was the subject of an extraordinary leak in early May, sparking demonstrations around the country, with an armed man arrested this month near the home of conservative justice Brett Kavanaugh.
'Never stop fighting'
Planned Parenthood, the leading abortion provider in the United States, vowed following the ruling to "never stop fighting" for those in need.
"We know you may be feeling a lot of things right now -- hurt, anger, confusion. Whatever you feel is OK. We're here with you -- and we'll never stop fighting for you," the organization tweeted.
Former Democratic President Barack Obama denounced the ruling, saying "it relegated the most intensely personal decision someone can make to the whims of politicians and ideologues -- attacking the essential freedoms of millions of Americans."
But former Republican vice president Mike Pence, a leading anti-abortion campaigner, welcomed it, saying the US right to abortion has been consigned to the "ash heap of history."
"This Supreme Court has righted a historic wrong," Pence said.
The three liberal justices on the court dissented from the ruling -- which came a day after the court ushered in a major expansion of gun rights in the country.
"Whatever the exact scope of the coming laws, one result of today's decision is certain: the curtailment of women's rights, and of their status as free and equal citizens," they said.
The court's ruling goes against an international trend of easing abortion laws, including in such countries as Ireland, Argentina, Mexico and Colombia where the Catholic Church continues to wield considerable influence.
The ruling was made possible by the nomination of three conservative justices to the court by former Republican president Donald Trump -- Neil Gorsuch, Kavanaugh and Amy Coney Barrett.
The case before the court was a Mississippi law that would restrict abortion to 15 weeks but while hearing the case in December several justices indicated they were prepared to go further.
According to the Guttmacher Institute, 13 states have adopted so-called "trigger laws" that will ban abortion virtually immediately.
Ten others have pre-1973 laws that could go into force or legislation that would ban abortion after six weeks, before many women even know they are pregnant.
Women living in states with strict anti-abortion laws will either have to continue with their pregnancy, undergo a clandestine abortion or obtain abortion pills, or travel to another state where the procedure remains legal.
Several Democratic-ruled states, anticipating an influx, have taken steps to facilitate abortion and clinics have also shifted their resources.
Travel is expensive, however, and abortion rights groups say any new restrictions will severely impact poor women, many of whom are Black or Hispanic.