The Family referendum has been resoundingly defeated with the result showing 67.7% voted No and 32.3% voted Yes.
The overall Referendum Returning Officer Barry Ryan made the official declaration in Dublin Castle shortly before 7pm.
The margin between those in favour and those against is expected to be 32.3%, or 533,982 votes.
Turnout was 44.36% and this marked a 19% drop since the 2018 abortion referendum.
Speaking on RTÉ's Six One News, Taoiseach Leo Varadkar said the referendum result was clear and both amendments would be rejected by a "considerable margin."
"We accept the result. We will respect the result fully, and as the head of Government and on behalf of the Government we accept responsibility for our failure to convince a majority of people to vote Yes," Mr Varadkar said.
The amendment was defeated in all but one of the 39 Dáil constituencies - Dún Laoghaire.
A margin of just 255 votes, ensured it was the only constituency to buck the national trend where 50.3% voted Yes and 49.7% voted No.
In neighbouring Dublin constituencies - Dublin-Rathdown and Dublin Bay South - the amendment was narrowly defeated.
In Dublin-Rathdown it was defeated by a margin of 371 votes where 50.6% voted No and 49.4% voted Yes.
It was narrowly defeated by 193 votes in Dublin Bay South with 50.35% voting No and 49.65% voting Yes.
The Family referendum has been defeated in the constituencies of all major party leaders - Fianna Fáil’s Micheál Martin (Cork South Central), Fine Gael’s Leo Varadkar (Dublin West), Green’s Eamon Ryan (Dublin Bay South) Sinn Féin’s Mary Lou McDonald (Dublin Central), Social Democrats’ leader Holly Cairns (Cork South-West), Labour’s Ivana Bacik (Dublin Bay South) and Aontú leader Peadar Tobín (Meath West).
Voters in Donegal delivered the highest No vote where 80% voted No and just 20% voted Yes.
The next highest No votes were recorded in Cavan-Monaghan (78%), Laois-Offaly (76%), Mayo (75.5%) and Longford-Westmeath (74.6%).
Speaking to RTÉ News, Tánaiste Mícheál Martin said he fully accepted the decision of the Irish people.
"It is a living document, one of the great attributes of that document is giving the power to the people to decide on whether or not there should be changes to the constitution," he said.
"The Government fully accepts the decision of the people, we will continue to work on supporting families and supporting care both in and outside of the home, we will continue to do that through budgets and through Government policy, and we will fulfil our mandate in that respect."
He said he did not think the referendum would go again as the people had spoken.
"The people have spoken emphatically, in respect of the two propositions, so certainly not in the lifetime of this Government," Mr Martin said.
Independent TD for Galway West Catherine Connolly has said that she saw a No-No result coming and that she felt disappointment with the Government.
Speaking at the count centre for Galway West in Salthill, Ms Connolly said: "They used propaganda to push two changes to our constitution in a manner that was patronising and patriarchal, and that women’s groups joined in and used that type of language is very upsetting for me.
"Is some of the language outdated? Absolutely, would I change some of the language? Yes."
Mr Varadkar said it was clear that both amendments had been defeated and "defeated comprehensively on a respectable turnout".
"As head of Government and on behalf of the Government, we accept responsibility for the result," he said.
"It was our responsibility to convince the majority of people to vote 'Yes' and we clearly failed to do so.
"I think we struggled to convince people of the necessity or a need for the referendum at all, let alone the detail and the wording. That's obviously something we're going to have to reflect on into the weeks and months ahead."
The Government is coming in for heavy criticism for its "lacklustre" referendum campaign, while opposition political party leaders - Sinn Féin's Mary Lou McDonald and Labour's Ivana Bacik - who advocated for Yes votes have been accused of being "marooned from their support base".
There has been a call from one Sinn Féin TD for Minister of State Roderic O'Gorman to resign over his handling of the Government's campaign.
However, Taoiseach Leo Varadkar has said he has "full confidence" in the minister.
From early morning a consistent pattern of No votes emerged from tallies in both referendums.
Earlier, Green Party leader Eamon Ryan spoke to reporters in the RDS Count Centre, before the referendum result, saying it looked like both referendums would be defeated.
"It does look like a No vote in both the Family and Care referendums," Mr Ryan said.
"The first thing to say is that we respect that. It's the voice of the people and in our Constitution, it's the people who are sovereign. It's they who decide what goes into our Constitution.
"We will have to wait until the final count has been done, but if it is a no vote in both, we will have to respect that."
Labour Party Leader Ivana Bacik, who had campaigned for Yes votes, said "responsibility ultimately lies with government".
"There was a very lacklustre government campaign and I think that's unfortunate," she added.
Limerick Sinn Féin TD Maurice Quinlivan said Minister O'Gorman should resign.
"This has been a catastrophic failure by Government who, in their arrogance, listened to nobody," he said.
"There was no prelegislative scrutiny, even though Sinn Féin and others requested this and the Children's Committee was willing to sit for as long as it took."
Live results from the Family and Care referendums
Aontú leader Peadar Toibín said today was not a No to single or cohabiting parents, rather a No to Government incompetency in relation to the development of the amendments.
He said that nobody knew what durable relationship was, even the Government ministers.
The Meath West TD said the political establishment now has serious questions to answer as "they are simply not listening to the people".
He said it was a David vs Goliath referendum and that in working class Labour and Sinn Féin heartlands, there were significant No votes.
"The leadership of those parties are marooned from their support base... That's a very dangerous place to be in advance of an election," Mr Toibín said.
As is often the case with referendum counts, there have been very few tally people in the 29 count centres around the country today.
Back in 2018, a number of miraculous medals were discovered in ballot boxes during the counting of votes in the Protection of Human Life in Pregnancy referendum.
Today, 11 medals that found their way into ballot boxes were found in boxes at the Dublin West count.
If the early tallies are anything to go by, it would take something miraculous for the official results to confirm anything other than resounding defeats in both referendums today.
