Taoiseach Micheál Martin has welcomed the outcome of the EU-UK summit in London, calling it a "landmark moment".
The EU and UK have reached an agreement to reset relations, which the British Prime Minister has claimed will add nearly £9 billion (€10.6bn) to the UK economy by 2040.
As part of the agreement, there will be a new sanitary and phytosanitary (SPS) deal on plant and animal products, which will not be time-limited.
According to the UK government, "some routine checks on animal and plant products will be removed completely", which will help reduce trade barriers between Northern Ireland and Britain.
UK Prime Minister Keir Starmer is hosting European Union chiefs for a landmark summit designed to usher in a closer relationship between Britain and the bloc, five years after Brexit.
Mr Martin said the outcomes from the talks deliver on the "shared commitment to reset relations between the EU and the UK".
"The UK is an important like-minded partner for the EU, and for Ireland, sharing our values and commitment to multilateralism and the international rules-based system," he said.
"It is essential that we work in partnership to address global challenges.
"I therefore welcome the conclusion of the defence and security partnership between the EU and the UK at today's summit."
He said the agreements "mark a new beginning in a positive and cooperative relationship between the EU and the UK which is essential for the pursuit of many areas of Ireland's national interest and is an important factor for stability in Northern Ireland".
The UK's decision to extend fishing rights for the EU fishing sector by another 12 years, "also provides certainty to Ireland's fishermen and women", said Mr Martin.
"Overall, a closer working relationship between the European Union and United Kingdom is good for Ireland, and for everyone," he said.
Northern Ireland Secretary of State Hilary Benn also welcomed the EU-UK reset agreement.
He said alignment with EU plant and animal standards will have significant benefits for businesses in Northern Ireland and Britain.
Speaking to RTÉ News, Mr Benn said that once the new arrangements are in place, "the movement of food and plants from GB across to Northern Ireland, the cheques, the costly paperwork, all of those things will go and the goods will move freely. That's why the supermarkets have welcomed what's been negotiated."
Mr Starmer described the deal as a "win-win" and hailed it as a "new era" for the UK and the EU.
"This deal is good for both sides," Mr Starmer told reporters at a joint press conference with EU chiefs Ursula von der Leyen and Antonio Costa following their summit.
Ms von der Leyen said the agreements sent a message that the countries of Europe stick together.
"The message we are sending to the world today is (that)...at a time of global instability, and when our continent faces the greatest threat it has for generations, we in Europe stick together," she said.
Meanwhile, Tánaiste Simon Harris said the summit "marks the beginning of an ambitious and productive new phase of EU-UK cooperation".
Mr Harris said both parties commitment to enhancing their relationship will deliver "real benefits for people in the UK and the EU alike".
The Tánaiste will chair the fifth meeting of the Government Trade Forum this afternoon which will consider the outcome of the EU-UK Summit.
Mr Harris will update the forum on trade policy developments, including at the EU-US level, and on his meetings with European Trade Commissioner Maroš Šefčovič and EU trade ministers in Brussels last week.
The new list of potential countermeasures in response to recent US tariff decisions will also be discussed.
