Fr Raymond A Browne, a parish priest in Co Roscommon, has been appointed Bishop of Kerry.
The announcement was made following morning mass at the cathedral in Killarney by the current bishop, Dr Bill Murphy, who is to retire.
The 56-year-old parish priest at Ballagh in Co Roscommon says he is deeply honoured that Pope Francis chose him as the new Bishop of Kerry.
Originally from Athlone in Co Westmeath, Fr Browne was ordained in 1982.
He says one of his first tasks will be to get to know the parishes, priests and people of the diocese.
He told those gathered outside the cathedral that he is conscious of the ongoing economic situation and how it has affected so many people throughout the country.
He prayed that all at national and local level will work together selflessly for the good of all and to give hope to all.
He referred briefly to the national debate on legislating for the X Case, and said the weeks ahead will be a decisive moment for Ireland.
He urged people to attend a national prayer vigil in Knock this weekend, with the theme "Choose life, mother and baby, we cherish them both",
Fr Browne, who has three sisters and three brothers, said he was told of the news nine days ago by Papal Nuncio Archbishop Charles Brown.
He said he was very surprised but delighted.
The present Bishop Murphy informed the Vatican two years ago that he planned to retire having reached the age of 75.
He said he was looking forward to his retirement from administrative duties and planned to do plenty of walking and reading.
Dr Murphy said he would not be retiring from the priesthood and will be available to priests if they are sick or on holidays.
Bishop Murphy had been Bishop of Kerry for the past 18 years.