The Children's Referendum has been passed with the support of 58% of voters, with just three of the country's 43 constituencies rejecting the proposed amendment.
However only 33.5% of those eligible to vote yesterday did so, which was the lowest turnout since the referendum on bail in 1996.
With such a low turnout the count was finished relatively quickly, with the national result announced at 2pm.
Three constituencies voted No - Donegal North East by 60%, Donegal South West by 56%, and Dublin North West by 50.4% - a margin of just 137 votes.
The margin in Cork North Central was even tighter - it voted Yes by just 47 votes.
The highest Yes vote was in Dublin South, with 73%, closely followed by Dublin South East and Dún Laoghaire.
Welcoming the result of the referendum, Taoiseach Enda Kenny said it was a "historic day for the children of Ireland".
He said passing the amendment would help "make childhood a good, secure and loving space for all our children".
Tánaiste Eamon Gilmore said he was disappointed at the low voter turnout, and that the Government may have to re-examine the issue of holding a referendum on a Saturday.
Minister for Children and Youth Affairs Frances Fitzgerald said passing the referendum will have a number of "very tangible, positive impacts".
"Children must now be listened to in certain court proceedings, when crucial decisions are being made about their future. The child's best interests will now be central to every decision taken on their behalf," she added.
Earlier, Editor of Alive magazine Fr Brian McKevitt, who campaigned for a No vote, said he accepted the democratic decision of the people.
However, he questioned the role of the media, including RTÉ, and their coverage of the campaign.
Fianna Fáil welcomed the result, but said questions must be asked of the Government's handling of the campaign.
Sinn Féin's Caoimhghín Ó Caoláin said the Government must now put in place the legislation and the resources needed to vindicate children's rights.
Welcoming the outcome, Yes for Children, the national campaign led by Barnardos, the ISPCC, the Children's Rights Alliance, and Campaign for Children said it was a statement by the people of Ireland that children matter and would provide a mandate for better laws, policy and services to improve the protection of children.
No campaigner Kathy Sinnott described the result as contaminated, and said it should be challenged in the courts.
The Government had broken the rules and had used public money to fund a Yes campaign, she added.