Prime Minister Leo Varadkar has previously said the eighth amendment, which makes abortion illegal unless there is a real and substantial risk to the life of the mother, was "too restrictive".
His government agreed today to hold the vote in "May or June 2018" -- just before the pope visits in August to attend the World Meeting of Families.
Abortion has always been illegal in Ireland but was inserted into the constitution in 1983 following a referendum, in which 67 per cent of voters were in favour and 33 per cent against.
However, women are free to travel abroad for abortions and thousands do so every year, mainly to England.
More From This Section
Opinion polls in recent years have consistently indicated strong support for reform in Ireland, which remains largely Catholic but where scandals have dented the church's authority.
Last year, the UN Human Rights Committee found Ireland's abortion laws "cruel, inhuman and degrading".
The referendum was announced as the government set out a timetable for several votes over the next two years, including one on Ireland's controversial anti-blasphemy law.
In 2015, Ireland became the first country in the world to legalise gay marriage in a referendum.
"Setting a timetable for the referendums to be held over the next two years will allow all involved in campaigning on the issues to plan ahead and to facilitate that public debate.