Abuse survivor Louise O'Keeffe has accepted the Taoiseach's apology on behalf of the Irish State.
The Cork woman won a case earlier this week that she brought to the European Court of Human Rights over abuse she suffered at a school in the 1970s.
In a statement, she says she's grateful for the speed of the Taoiseach's apology and she graciously accepts it.
"I appreciate very much his apology and I suppose I appreciate the fact that he did it quickly," she said.
"I would never have looked for an apology for myself.
"I would have looked for an apology for all victims of abuse in schools because there are many of them who have not come forward."
Enda Kenny said that the judgement in her case is exceptionally complex and will be studied by the Government.
"I would like to say to Louise O'Keeffe that I apologise for what happened to her, and for the horrendous experience that she had to go through," he said.
The State fought her claims and initially won in the High Court and Supreme Court in Dublin, before going on to the Strasbourg court where Ms O'Keeffe triumphed.
She told RTÉ Radio she would not have pursued the battle if she had been given an apology.
She urged the Government to act on the human rights judgment.
"I'm simply one of hundreds who have come forward and those who have not," she said.
"An apology is for everyone because I know I was not alone."
Tánaiste Eamon Gilmore also apologised during questions in the Dáil.
"I admire Louise O'Keefe and I join with the Taoiseach in apologising to her," he said.
The landmark lawsuit against the Irish State could have massive ramifications for 135 other survivors of abuse in school, including in terms of compensation, who alleged similar liabilities.
Ms O'Keeffe's former principal Leo Hickey was prosecuted in the 1990s for historic abuse against pupils.
He was charged with 386 criminal offences of sexual abuse involving 21 former pupils of the school, near Kinsale, Co Cork.
In 1998, he pleaded guilty to 21 sample charges and was sentenced to three years in jail.
The European court found that Ireland's system of detection and reporting of abuse was ineffective in the 1970s as it allowed more than 400 incidents of abuse over such a long period.
It said if adequate action had been taken in 1971 when the first complaint against Hickey was made, Ms O'Keeffe might have not been abused by him.