The late Pope Benedict managed to attend mass in his room last night just hours before he passed away.
The German theologian, 95, was the first pope in 600 years to resign in 2013, citing his ailing health.
A Vatican spokesman announced Pope Emeritus Benedict XVI's death "with pain" this morning.
His passing came just hours after the Vatican reported positively on Benedict's health, saying he had managed to rouse himself from his ongoing illness to take mass in his room.
The Church said he was in "stationary condition" at the time of the announcement.
Spokesman Matteo Bruni said in a statement: "Last night the Pope Emeritus was able to rest well.
"He also participated in the celebration of Holy Mass in his room yesterday afternoon. At present his condition is stationary."
Pope Francis surprised followers and the world on Wednesday when he asked them to pray for his "very sick" predecessor.
The rapid deterioration of his health was also confirmed by spokesman Bruni shortly after Francis's announcement.
He said: “Regarding the health conditions of the emeritus pope, for whom Pope Francis asked for prayers at the end of his general audience this morning, I can confirm that in the last hours, a worsening due to advanced age has happened.
“The situation at the moment remains under control, constantly monitored by doctors.”
Pope Benedict XVI, originally called Joseph Alois Ratzinger, was born in Germany to a policeman father and a hotel cook mother.
As a teenager he was drafted into the army, although he has claimed that he never took part in combat or fired a shot.
After the war he continued his education in a seminary, having had a desire to enter the priesthood at an early age.
In June 1951 he was ordained as a priest and began a career in academia, teaching theology at universities in Germany.
He was elected on April 19, 2005 at the age of 78 - the oldest to have done so since Pope Clement XII 1730.
Pope Benedict XVI, who was 95 at the time of his death, was the head of the Catholic Church between April 2005 and February 2013.
He resigned from the post aged 85 in 2013, making him the first to quit in 600 years.
He resigned from the Church's top spot, saying his old age had limited his abilities to carry out his sacred duties.
Benedict had lived since his resignation in a monastery on the grounds of the Vatican.
The former pontiff had suffered bad health in the years leading up to his death - in 2020 there were reports of the pope having become seriously ill with shingles with reports he could "barely speak".
Benedict, 93, fell ill after returning to the Vatican from Germany where he visited his sick brother, Passauer Neue Presse reported in August of that year.
Benedict went to his native Bavaria in June to pay his brother Georg Ratzinger a final visit.
Ratzinger, aged 96, died shortly afterwards.
It was Benedict's first trip outside Italy since 2013, the year he resigned the papacy.
