Former Pope Benedict, who in 2013 became the first pontiff in 600 years to step down, died on Saturday aged 95 in the Mater Ecclesiae Monastery in the Vatican where he had lived since his resignation.
This is according to a spokesman for the Holy See.
"With sorrow, I inform you that the Pope Emeritus, Benedict XVI, passed away today at 9:34 in the Mater Ecclesiae Monastery in the Vatican. Further information will be provided as soon as possible," the spokesman said in a written statement.
The Vatican said his body will lie in state from Monday in St.Peter's Basilica. The Vatican has painstakingly elaborate rituals for what happens after a reigning pope dies, but no publicly known ones for a former pope.
Earlier this week, Pope Francis disclosed during his weekly general audience that his predecessor was "very sick" and asked people to pray for him.
For nearly 25 years, as Cardinal Joseph Ratzinger, Benedict was the powerful head of the Vatican's doctrinal office, then known as the Congregation for the Doctrine of the Faith (CDF).
Conservatives in the Church have looked to the former pope as their standard bearer, and some ultra-traditionalists even refused to acknowledge Francis as a legitimate pontiff.
They have criticised Francis for his more welcoming approach to members of other communities and to Catholics who divorced and remarried outside the Church, saying both were undermining traditional values.