Ireland's ninth president will be Labour's Michael D Higgins after the first official count gave the veteran politician 40% of the vote.
The resounding victory - 701,101 votes out of 1.77 million - was secured with a tidal wave of eleventh hour support for the 70-year-old from Galway after controversy over his biggest rival's political fundraising past.
Mr Higgins, a former government minister, came from 15 points behind in the opinion polls last weekend to steal the landslide success, with all other candidates conceding defeat.
President-elect Mr Higgins said his term in office would be about inclusion, ideas and transformation: "I feel a little overwhelmed. I'm very, very happy. It is something I prepared for, something I thought about for a long while.
"I am very glad as well that it is a presidency built on a campaign that emphasised ideas. I hope it will be a presidency that will enable everybody to be part of and proud of."
Mr Higgins paid tribute to the other candidates, and said many of their ideas would be incorporated into his presidency.
Two independents at the bottom of the polls, Mary Davis, who headed the Irish division of Special Olympics, and Dana Rosemary Scallon, former Eurovision winner and Eurosceptic MEP, were excluded on the first count.
Mr Higgins will be inaugurated on Armistice Day, November 11 - the day after current President Mary McAleese leaves office.
His biggest challenger had been opinion poll-topper Sean Gallagher, whose support collapsed from a high of 40% just last weekend. The businessman - a former fundraiser for the Fianna Fail party which was widely blamed for the country's economic woes - ran into a storm of controversy on Monday night amid allegations he was a "bag man" soliciting and collecting donations.
Sinn Fein's Martin McGuinness, who was running third in the poll and secured a tactical victory, dropped the bombshell in a live RTE debate that Mr Gallagher had requested and personally received a 5,000 euro (£4,390) cheque from a businessman with a conviction for tax fraud and fuel smuggling.