His historic trip is only the second by a serving pope and comes as the Vatican has been in the spotlight for the wrong reasons, following sex abuse scandals in the United States, Chile and Australia.
The reason for the Pope’s visit is the World Meeting of Families, which is being held in Dublin this year.
It has taken place every three years since Pope John Paul II established it in 1994 to strengthen the bonds between families and bear witness to the “crucial importance” of marriage and the family.
There will be many speakers and seminars at events across the capital and the highlight will be the Pope taking part in a session.
As part of it, the Festival of Families is choreographed as a celebration of family life in music song, dance and the spoken word.
The Pope will hear testimonies from families and see performers such as Italian tenor Andrea Bocelli. He will visit also Irish President Michael D Higgins at his home in Phoenix Park then see Taoiseach Leo Varadkar at Dublin Castle for a meeting lasting around 15 minutes.
The subject of his conversation with Mr Varadkar has been the subject of speculation, including whether the Irish premier will raise the clerical sex abuse scandals that have rocked the Catholic Church.
The Pope is also expected to visit St Mary’s Pro-Cathedral.
He will undertake a private trip to a day centre for homeless families.
Tomorrow Francis will follow in the footsteps of John Paul II, who visited the Knock shrine in 1979, a century after an apparition was said to have occurred.
The final event of the pontiff’s visit will take place at Phoenix Park, site of a towering papal cross where John Paul II said mass.
On September 29, 1979, more than a million people formed the largest Irish gathering in history.
This time, half a million are expected.
Protests are expected to take place, including at Dublin’s Garden of Remembrance.