"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.
Earlier this week, Pope Francis disclosed during his weekly general audience that his predecessor was "very sick", and asked for 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 criticized Francis for his more welcoming approach to members of the LGBTQ+ community and to Catholics who divorced and remarried outside the Church, saying both were undermining traditional values.