Taoiseach Micheál Martin has described Ireland's place on the United Nations Security Council as an "enormous responsibility and honour". Ireland officially took its seat on the Security Council on January 1 for a two-year period.
This will be Ireland's fourth time on the UN Security Council, having previously served in 1960, 1980-81 and 2001-02.
"Ireland is today taking up our seat on the United Nations Security Council," Mr Martin said. "It is an enormous responsibility and honour to serve for the next two years.
"When we stood for election we promised to bring the values of empathy, partnership and independence to bear. They will guide our work now.
"Members of the Irish Defence Forces have served under the UN flag with great distinction around the world.
The UN flag is to fly at Leinster House for the duration of Ireland's tenure on the council.
It joins newly elected members Kenya, India, Mexico and Norway alongside existing elected members Estonia, Saint Vincent and the Grenadines, Niger, Tunisia and Vietnam.
There are also five permanent members of the Council: China, France, Russia, the UK and the US.
Ireland's areas of responsibility are expected to include humanitarian issues in Syria and West Africa, as well as issues of women, peace and security and climate security.
Foreign Affairs Minister Simon Coveney said: "The United Nations is at the heart of Irish foreign policy.
"Whether it is through our unbroken record of UN peacekeeping since 1958 or our leading roles in disarmament and non-proliferation, we know what can be achieved when countries work together.
"We take our seat on the council at a very challenging time but we are determined to play our part to build the trust and political will necessary to achieve progress in even the most intractable conflicts.
"Membership of the UN Security Council is an opportunity for Ireland to make a significant international contribution, to strengthen our relations with key partners, and to project our values on the global stage.
"It is in keeping with our long-standing tradition of an independent and principled foreign policy and support for the UN."
Ireland saw off competition from Canada to secure one of the two "western bloc" seats on the council, along with Norway.
A high-profile campaign saw diplomats invited to a U2 concert at Madison Square Garden in New York.