The dramatic move comes after a vote of no confidence by seven Labour TDs following the disastrous party results in the local and European Parliamentary elections.
The Labour Party is the junior party in Ireland's coalition government. Sinn Fein and independents took 45 percent of the vote in the European and local elections. Labour was wiped out at Europe and at home while Fine Gael has seen its general election support of 33 percent cut by a third.
The motion of no confidence in Gilmore was tabled by TDs Ciara Conway, Dominic Hannigan, Michael McNamara, Ged Nash, Derek Nolan, Aodhan O Riordan, Arthur Spring, along with Senator John Gilroy.
Speaking to the press, flanked by members of his party, Gilmore said “At 10.30am this morning I informed the General Secretary of the Labour Party I intended to stand down as leader of the Labour party.
“I’ve had the honor and privilege to lead the Labour party for seven years.
“I asked party to take on responsibility of government. I believed as citizens and a party we had a responsibility to put the country first.
“I still believe that was the right the decision, and I’m proud of the progress we have made.”
Gilmore said he made this decision having consulted with his family and added that he intended to contest the next General Election.
He said “The party, and the government, must move on.
“We must, and we will, continue to put the country and the needs of the people first.
“There is more to do, and I intend to be part of it.”
He added that job of rebuilding the Labour Party would be best left to new leadership. He refused to endorse any candidate as his replacement.
Earlier in the day the Taoiseach (Prime Minister) Enda Kenny told the press that he did not know what the Gilmore statement would entail and said “I've just tried to ring him, I can't get through."
The statement by the Labour members read:
"Dear Chairman, We the undersigned propose the motion that The Parliamentary Labour Party does not retain confidence in The Party Leader.
"Submitted by Deputy Ciara Conway TD , Senator John Gilroy , Deputy Dominic Hannigan TD , Deputy Michael McNamara TD , Deputy Ged Nash TD , Deputy Derek Nolan TD , Deputy Aodhan O Riordan TD , Deputy Arthur Spring TD .
"We wish this motion to be discussed on Wednesday 28th of May 2014 at the PLP [the scheduled Labour Party meeting].”