Pope John Paul II and Pope John XXIII will be declared saints on 27 April 2014, Pope Francis has announced.
The Pope said in July that he would canonise his two predecessors, after approving a second miracle attributed to John Paul.
Polish John Paul, the first non-Italian pope for more than 400 years, led the Catholic Church from 1978-2005.
Pope John was pontiff from 1958-1963, calling the Second Vatican Council that transformed the Church.
The decision to canonise the two at the same time appears designed to unify Catholics, correspondents say.
John Paul II is a favourite of conservative Catholics, while John XXIII is widely admired by the Church’s progressive wing.
‘The good pope’
John Paul stood out for his media-friendly, globetrotting style. He was a fierce critic of communism, and is credited with helping inspire opposition to communist rule in eastern Europe.
John Paul has been on a fast track to sainthood since his death, when crowds in St Peter’s Square chanted “santo subito” (“sainthood now”).
During his own papacy he simplified the process by which people are made saints, and created more of them than all previous popes combined.
John XXIII is remembered for introducing the vernacular to replace Latin in church masses and for creating warmer ties between the Catholic Church and the Jewish faith.
He has a big following in Italy, where he is known as Il Papa Buono, the good pope.
The BBC’s David Willey reports from Rome that Pope John was in many ways similar to Pope Francis, a humble, down-to-earth man with a fine sense of humour.
Two living popes are expected to be present at the canonisation ceremony: Francis, who will officiate, and Pope Benedict, who retired earlier this year.
The double canonisation will be the first in the Church’s history.
Pope Francis approved John XXIII’s canonisation despite the fact that no second miracle had been attributed to him – usually a requirement for sainthood.