Ombudsman Emily O'Reilly has been elected as European Ombudsman at a vote in the European Parliament in Strasbourg.
The European Ombudsman investigates public complaints concerning European Institutions and various EU agencies.
She is the first woman to hold the position.
President Michael D Higgins congratulated Ms O'Reilly on her election.
He thanked her for her committed service as Irish Ombudsman and said her election reflects the "very high regard in which she is held across Europe."
Taoiseach Enda Kenny also congratulated Ms O'Reilly.
He said the full support of Irish MEPs for her was "testament to her many years of work as Irish Ombudsman".
Ms O'Reilly, who has been Ireland's Ombudsman since 2003, came joint-first in a preliminary vote yesterday.
The other leading contender was Dutch MEP Ria Oomen-Ruijten, a member of the Parliament's largest political grouping, the centre-right European People's Party.
Ms O'Reilly has said she hopes to raise the profile of the office of European Ombudsman after her election to the position by the European Parliament.
Speaking on RTÉ's News at One, Ms O'Reilly said she expects the office to deal with more "meaty issues" during her tenure, as EU institutions are playing a more prominent part in the lives of ordinary citizens.
She said: "The office is slightly smaller than my own. It has about 60 staff in it. It is very busy in terms of the number of people who come to it.
"Obviously, a lot of the complaints that it gets don't exactly fit into its remit. A lot of people in Europe think it's an appeal body for the member states, which it isn't.
"But increasingly it's dealing with much more complex complaints. It's really moving out from the margins, where it was dealing with individual complaints, to dealing with much more meaty issues.
"Two of the words I was using were visibility and impact, because if nobody knows it's there, it could be doing fantastic work on a small number of complaints."
Ms O'Reilly welcomed the cross-party support she received from MEPs in Strasbourg and said Ireland's response to the recession had helped her candidacy.
She said: "I suppose it came at a good time. I think if I had been competing for this two years ago when Ireland's name and reputation wasn't so great, it might have been more difficult.
"From what I have picked up from conversations with MEPs from all across the various countries, there was a generally reasonably high regard for the way Ireland is dealing with the recession and for the way it handled the (EU) presidency."