Ivana Bacik has been elected to the Dáil.
The Labour senator has won the Dublin Bay South by-election, after picking up over 30% of first preference votes.
The final count confirmed she's now heading to Dáil Éireann after nearly 14 years in the Seanad.
Ahead of the official declaration, Ms Bacik said she was "over the moon" to win the by-election.
She said: "I'm just so deeply honoured and grateful to have apparently received such overwhelming support from across my home constituency here."
Fine Gael's James Geoghegan finished in second place, with around 26.2% of first preference votes.
It leaves Fine Gael without a seat in the constituency, as the by-election was triggered by the decision of former minister Eoghan Murphy to resign from the Dáil.
Sinn Féin's Lynn Boylan finished in third place, followed by Green Party candidate Claire Byrne.
It was a poor showing for Fianna Fáil, whose candidate Deirdre Conroy secured just 4.6% of first preference votes.
Fianna Fáil director of elections Jim O’Callaghan today said the party will now have to “think about” whether Micheál Martin is at the helm for the next general election.
However, the Taoiseach this evening insisted it's still his intention to lead the party into that vote.