Pope Francis died on Monday aged 88, a day after making a much hoped-for appearance at Saint Peter's Square on Easter Sunday, the Vatican said in a statement.
"Dearest brothers and sisters, it is with deep sorrow that I must announce the death of our Holy Father Francis," said Cardinal Kevin Farrell in the statement published by the Vatican on its Telegram channel.
"This morning at 7:35 am [local time] the Bishop of Rome, Francis, returned to the home of the Father.
"His entire life was dedicated to the service of the Lord and His church."
Francis's death came just a day after he delighted the crowds of worshippers at the Vatican on Easter Sunday with an appearance on the balcony at Saint Peter's Basilica despite still convalescing after a severe illness.
Francis had come close to dying twice earlier this year while suffering from pneumonia.
He spent 38 days in hospital before he was released on March 23.
On Sunday he wished the crowds on Saint Peter's Square a "Happy Easter" as he waved and in his traditional "Urbi et Orbi" ("To the City and the World") benediction he called for freedom of thought and tolerance.
Francis was known as a liberal reformer, making headlines across the globe by permitting the blessing of same-sex couples and promoting global action on climate change.
Francis worked as, a janitor and a chemical technician in the food-processing industry before entering the seminary.
He was outspoken about clergy abuse and called on the Catholic Church to "act decisively" against paedophile priests just months after his 2013 appointment.
What happens now?
Cardinals, including Australia's Mykola Bychok, will now be summoned to Rome to choose Francis's successor.
According to tradition, the pope's death will be ritually confirmed by Vatican officials, and nine days of mourning will be declared.
The burial usually happens between the fourth and the sixth day. Popes are usually buried at St Peter's Basilica in Vatican City, but Francis had said he wanted to be interred in the Basilica of Santa Maria Maggiore, outside the Vatican's walls.
Once in Rome, cardinals will go through the process of a papal conclave to vote on the next pope.
Cardinals are forbidden from having any contact with anyone outside the conclave, at risk of excommunication.
'Remembered for his compassion'
Ukrainian-born Melbourne Bishop Mykola Bychok, who is now Australia's highest ranking Catholic, was elevated to the position of cardinal by Pope Francis.
He described the Holy Father as a strong defender of life who bought the church closer to people, in a statement.
"When I was raised to the College of Cardinals, I asked the Holy Father to pray for Ukraine, to help free stolen Ukrainian children and to pray for me in my new mission as an Australian – Ukrainian Cardinal."
"I now pray, that Pope Francis may intercede before Christ for the people of Australia and Ukraine.
"I am grateful for the late Holy Father's frequent appeals for a just peace in Ukraine and for the efforts of the Holy See that he oversaw, known and secret, that in some way helped bring relief to the imprisoned and suffering."
US Vice President JD Vance, who met with the pope at the Vatican on Easter Sunday, said he will remember the pope for the homily he gave in the very early days of COVID.
"I just learned of the passing of Pope Francis. My heart goes out to the millions of Christians all over the world who loved him.
"I was happy to see him yesterday (Sunday), though he was obviously very ill."
Prime Minister Anthony Albanese said Francis was "close to all Australians".
"Pope Francis's compassion embraced all humanity, and today he will be mourned by Catholics and non-Catholics alike," he said.
"He urged us to remember all we hold in common, and he asked the world to hear the cry of the Earth, our common home."
Opposition Leader Peter Dutton responded to the death of Pope Francis in a statement.
"With God, may Pope Francis rest in peace," he said.
"On behalf of the Coalition, I express my condolences to Australians of Catholic and Christian faith upon the sad news of the death of the 266th pontiff.
"His Holiness, Pope Francis, served God with the utmost devotion throughout his life.
"He was the first pope from the Jesuit order and the first Latin American pope.
"He lived frugally and simply."
Italian Prime Minister Giorgia Meloni said news of Pope Francis's death was cause for great sadness because of the departure of "a great man, a great shepherd".
"The pope and I had a more active relationship than was apparent," she said.
"It went well beyond our respective institutional roles," she said.
"He was able to give comfort in very difficult moments, I have many memories of the pope," she added in a broken voice on an Italian state broadcaster.
"I had the privilege of enjoying his friendship, his advice, his teachings, which never ceased not even during times of trial and suffering," Ms Meloni said in a statement.
French President Emmanuel Macron said the pontiff "always sided with the most vulnerable and the most fragile".
"In this time of war and brutality, he had a sense for the other, for the most fragile," he said.
The bells of Paris' Notre Dame cathedral tolled 88 times in memory of Pope Francis.
City authorities will turn off the lights on the Eiffel Tower on Monday night in memory of the pope, BFM TV reported.
Germany's Chancellor-in-waiting Friedrich Merz said Pope Francis would be remembered for tireless commitment to the society's weakest members.
"He was guided by humility and faith in God's mercy," Mr Merz said in a post on X.
Pope Francis was a man of deep faith, peace and compassion who fostered ties with the Jewish world, Israel's President Isaac Herzog said on Monday, in a condolence message to the Christian world and its communities in the Holy Land.
"A man of deep faith and boundless compassion, he dedicated his life to uplifting the poor and calling for peace in a troubled world," Mr Herzog said of Francis.
"I truly hope that his prayers for peace in the Middle East and for the safe return of the hostages (in Gaza) will soon be answered," Mr Herzog said on X.
Cardinal Pablo Virgilio David, President of the Catholic Bishops conference of the Philippines found out the pope had died just 10 minutes after his passing.
"Oh my God. I am so shocked by this."
"Let us please ring the bells of our churches and call our people to prayer for the eternal repose of the Holy Father Pope Francis who passed on just about 10 minutes ago."
