He was ending a two-day visit to the Republic of Ireland by celebrating a Mass at Dublin’s Phoenix Park.
The Argentine Pope asked forgiveness for the “abuses in Ireland, abuses of power, conscience and sexual abuses” perpetrated by Church leaders.
It was the first papal visit to Ireland for 39 years.
He said no-one could fail to be moved by stories of those who “suffered abuse, were robbed of their innocence and left scarred by painful memories”, and reiterated his wish to see justice served.
The Vatican estimated that 300,000 people flocked to Phoenix Park for the Mass to close the World Meeting of Families, a global Catholic gathering that is held every three years. Other crowd estimates were lower.
Pope Francis used the penitential rite of the Mass to list a litany of different types of abuse and mistreatment inflicted on Irish people by Church figures, and the cover-ups of sex crimes.
On each occasion he asked for forgiveness, the congregation applauded.
The Irish Catholic Church has been rocked by revelations of pedophile priests, sexual abuse in Catholic-run orphanages, and the exploitation of women in mother-and-baby homes.
During the first day of his trip, Pope Francis used a speech at Dublin Castle to express his shame at the Catholic Church’s failure to adequately address the “repellent crimes” of sex abuse by clergy.
He later met eight survivors of sexual abuse, reportedly telling them he viewed clerical sex abuse as “filth”.
Mr. Varadkar delivered a strong warning to the Pope to take action against clergy involved in child abuse and in keeping it secret.
Pope Francis told the crowds at Knock that the “open wound of abuses” committed by the Roman Catholic Church challenged it to be firm in the pursuit of truth and justice.
He said in his prayer to Mary, the mother of Jesus, he had “presented to her in particular all the victims of abuse of whatever kind committed by members of the Church in Ireland”.
Later, in Phoenix Park, he also asked “forgiveness for those single mothers who went looking for their children who had been taken away. It is not a mortal sin.”
I ask our Blessed Mother to intercede for the healing of the survivors of abuse and to confirm every member of our Christian family in the resolve never again to permit these situations to occur.
— Pope Francis (@Pontifex) August 26, 2018
Meanwhile, a former top Vatican official called on the Pope to resign, saying the pontiff knew about allegations of sex abuse by a prominent US cardinal for five years before accepting his resignation last month.
In an 11-page letter, Archbishop Carlo Maria Vigano said he had told Pope Francis in 2013 that Cardinal Theodore McCarrick had faced extensive accusations of sexually abusing lower-ranking seminarians and priests.
The Vatican has not responded to these claims – and Archbishop Vigano has not produced any written or other evidence to verify his conversation with Pope Francis.
Correspondents say the timing of his letter, released to coincide with the Pope’s landmark visit to Ireland, has raised questions about whether this is a coordinated attack from traditionalists within the Catholic hierarchy who oppose Pope Francis.