Fianna Fail leader hails Higgins
Irish opposition leader Micheal Martin sent his congratulations to Michael D Higgins within five hours of count centres opening.
The leader of Fianna Fail, Ireland's once domineering political party, vowed Mr Higgins would have the support of the Fianna Fail community when he takes the role of being the ninth president.
Mr Martin said it was an exceptionally proud day for Mr Higgins, his wife Sabina and their family.
"I have known Michael D Higgins for many years and he will make an excellent president and ambassador for Ireland," he said.
"I want to wish him well in his presidency for which he will have my full support and that of the Fianna Fail community across the country."
However, it was Mr Martin's decision not to run a candidate in the presidential campaign which prompted a bitter debate and deep divisions within his own parliamentary party.
Deputy leader Eamon O Cuiv - grandson of former president Eamon De Valera - had been touted as a possible candidate. In August Mr Martin approached Irish veteran broadcaster Gay Byrne to consider running for the party, without the knowledge of senior figures.
But within weeks the dwindling number of supporters were left shocked when the party opted not to enter a candidate after being decimated in the February general election.
Mr Martin, a former foreign minister, said he worked closely at the time with Mr Higgins who was Labour's foreign affairs spokesman.
"His command of global issues and commitment to human rights was significant and I have no doubt that human rights and humanitarian issues will be a significant part of his presidency," he added.