The Republic of Ireland has voted overwhelmingly to overturn the abortion ban by 66.4 percent to 33.6 percent.
A referendum held on Friday resulted in a landslide win for the repeal side.
Currently, abortion is only allowed when a woman's life is at risk, but not in cases of rape, incest or fatal foetal abnormality.
The Eighth Amendment, which grants an equal right to life to the mother and unborn, will be replaced.
The declaration was made at at Dublin Castle at 6:13pm local time.
The only constituency to vote against repealing the Eight amendment was Donegal, with 51.9 percent voting against the change.
A vote in favour of repeal paves the way for the Dáil (Irish Parliament) to legislate for change which would see the introduction of a much more liberal regime.
In 2015 the country voted overwhelmingly to legalise same-sex marriage in a historic referendum.
Reacting to early indications of the result, the taoiseach (prime minister) Leo Varadkar, who campaigned in favour of liberalisation, said: "What we've seen is the culmination of a quiet revolution that's been taking place in Ireland over the past 20 years."
He added that Irish voters "trust and respect women to make the right choices and decisions about their own healthcare".
Counting began at 9am.
After the polls were published, one of the main anti-abortion campaigns conceded it had lost the vote.
The Save The 8th campaign described the result as a "tragedy of historic proportions".
"The unborn child no longer has a right to life recognised by the Irish state," said its spokesman John McGuirk.
However, he vowed that No campaigners would continue to protest, "if and when abortion clinics are opened in Ireland".
The leader of the main Irish opposition party, Micheál Martin of Fianna Fáil, said the vote was the "dawn of a new era".
He said he had wrestled with the issue, but added the people had made the right decision and it would mean better care for women in Irish hospitals.
Sinn Féin president Mary Lou McDonald, whose party campaigned in favour of a Yes vote, said: "We have, without doubt, done right by Irish women for this generation and many to come."
Amnesty International hailed the result as a "momentous win for women's rights" that "marks the beginning of a new Ireland".
The vote will have repercussions for women north of the border, as Northern Ireland has the strictest abortion laws in the UK.
Cases of rape, incest and fatal foetal abnormality are not considered grounds for a legal termination.
The UK's Women and Equalities Minister Penny Mordaunt said the predicted landslide vote gave "hope" to Northern Ireland.
"It's hypocritical, degrading and insulting to Northern Irish women that we are forced to travel for vital healthcare services but cannot access them at home," she said.
"We cannot be left behind in a corner of the UK and on the island of Ireland as second-class citizens."
Former Northern Ireland health minister Jim Wells said the expected result was a "grave threat" to the unborn child in Northern Ireland.
Mr Wells, a Democratic Unionist Party (DUP) politician, claimed it was "inevitable" that abortion clinics would be set up in border towns to "promote their services to Northern Ireland women".
"It will be much easier to terminate a child's life if this can be done at a clinic in Dundalk or Letterkenny rather than flying to London or Manchester," he added.
Meanwhile, in New Zealand Heather Byrne watched the event last night in Wellington with a number of other Irish yes supporters.
She wants women to have a choice.
"If we ever move back home to Ireland, we want to know we've got the choice over our own bodies... and at the moment that's not happening... they're having to fly abroad for it," she said.
Eimear Connolly said it was a good step forward for the country.
"It will give women equal rights... which is not just an Irish topic, but a global one," she said.
- BBC / RNZ