Gino Kenny of People Before Profit/Anti-Austerity Alliance was the fourth and final TD home from the Dublin Mid-West constituency.
Having polled 7,911 votes he was deemed elected without reaching the 8,621 quota. He is the first TD from Neilstown, one of the most deprived areas in the State.
Also elected on the 12th and final count was John Curran of Fianna Fáil, who exceeded the quota with 9,497 votes.
Much earlier in the day Eoin Ó Broin of Sinn Féin topped the poll, with 9,782 first preferences.
Minister for Justice Frances Fitzgerald was also elected on the first count, with 9,028 votes.
Mr Kenny described his election as a “very, very proud day for my community, for my family and for the party”. He said he was “proud to live in Neilstown”.
"The people of north Clondalkin have been waiting for this day. It's day of retribution against the Government, a day of punishment for Labour who have become apologists for Fine Gael. "
Mr Curran said Fianna Fáil had “listened to the people” over the past five years. “There’s a deep disillusionment.”
Asked whether he thought a government could be formed, he said he was not putting away his election posters yet.