Sinn Fein's Martin McGuinness had branded her questioning "unfair and totally out of order" during a presidential debate.
But the Broadcasting Authority of Ireland has ruled in favour of Miriam O'Callaghan over her treatment of the Sinn Fein candidate in a 'Prime Time' presidential debate last October.
The BAI received 10 complaints in relation to how the RTE host treated Mr McGuinness during the October 13, 2011, transmission, amid claims that she unfairly quizzed him about his membership of the IRA and what he knew about the killing of Private Patrick Kelly in 1983.
However, after a full investigation by the BAI, none of the 10 complaints have been upheld.
Mr McGuinness claimed the questioning he faced was "unfair and totally out of order".
He had been further annoyed when the other six candidates were asked to give their opinions on whether he was suitable for the presidency.
Northern Ireland's Deputy First Minister was so outraged that, after the broadcast, he asked for a meeting with Ms O'Callaghan in her dressing room where it is understood that he complained strongly to her.
During the broadcast Ms O'Callaghan had asked candidates about their religious beliefs, and then turned to Mr McGuinness, and noting his IRA past, said: "How do you square, Martin McGuinness, with your God, the fact that you were involved in the murder of so many people?"
The Sinn Fein MP said at the time that the question was a disgrace.