The Pope arrived at the Divine Mercy Sanctuary in Lagiewniki, a district of Krakow, as part of celebrations at World Youth Day.
Pope Francis declared 2016 a Holy Year of Mercy, where the Catholic Church puts special emphasis on teaching and practising God's grace.
The pontiff prayed in the chapel at the Sanctuary and blessed children and the infirm who were waiting for him there.
Later he went to the nearby Sanctuary of St. John Paul II, also in the Lagiewniki district.
In the evening he and hundreds of thousands of other pilgrims will attend a special prayer vigil also dedicated to the theme of mercy.
Pope Francis' first trip to Eastern Europe, and World Youth Day itself, both finish on Sunday.
