The Irish government is also planning votes to remove the country's anti-blasphemy law and to reduce the time couples must spend apart before divorcing.
Prime Minister Leo Varadkar has previously said the eighth amendment of the constitution, which makes abortion illegal unless there is a real and substantial risk to the life of the mother, was "too restrictive".
His government decided on Tuesday a referendum - which must be agreed by parliament - should take place 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.
The eighth amendment recognises the equal right to life of the unborn child and the mother, and a woman convicted of having an illegal termination faces 14 years in prison.
However women are free to travel abroad for abortions and thousands do so every year, mainly to England.
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.
Thousands of people are expected in Dublin on Saturday for the annual "March for Choice", declaring: "We are ready for change."
"We need access to free, safe and legal abortion for all who need or want it. And we need it now," organisers said.
The Abortion Rights Campaign said it "cautiously" welcomed the announcement.
"It depends on the wording of the referendum," spokeswoman Linda Kavanagh told AFP, fearing that it could be watered down from broad access to abortion.
Meanwhile Cora Sherlock, spokeswoman of the Pro-Life Campaign, told AFP: "If the eighth amendment were to be amended or repealed, we would inevitably end up with a situation similar to every other country which introduced abortion on 'restrictive' grounds but subsequently ended up with abortion on wide-ranging grounds."
Consideration by the people
The Irish constitution can only be amended by referendum, and in 2015 it became the first country to legalise gay marriage that way.
The government set out a timetable on Tuesday for several votes over the next two years, including on reducing the time couples must wait before a divorce from four to two years.
In October 2018, it proposes a referendum on the constitutional amendment which makes illegal the "publication or utterance of blasphemous, seditious or indecent matter".
At the same time, it proposes a vote to repeal or change a section relating to a woman's duties in the home, perhaps to make it gender neutral and to include other caring responsibilities.
"Any amendment to our constitution requires careful consideration by the people," Varadkar said in a statement.
"They should be given ample time to consider the issues and to take part in well-informed public debate," he said.
"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."
Share
