Pope Francis started his first day as the new pontiff with an impromptu early morning visit to pray for guidance at Rome's main Santa Maria Maggiore basilica dedicated to the Virgin Mary, sending his new security officials into a frenzy.
The world's 1.2bn Catholics are getting to know the first ever pope from Latin America, who is being described as an open-minded conservative and a frugal-living champion of the poor.
Father Ludovico Melo, a priest who prayed with the pope, said: "He spoke to us cordially like a father. We were given 10 minutes' advance notice that the pope was coming."
Formally know as Cardinal Jorge Mario Bergoglio, he now faces a gruelling schedule over the coming days, with a visit planned to his predecessor Benedict XVI at his retreat at Castel Gandolfo outside Rome, as well as audiences with his cardinals, the media and the faithful.
Last night thousands of people gathered in St Peter's Square to witness the announcement of the new Pope.
He then appeared on the balcony over the entrance to St Peter's basilica more than an hour after white smoke poured from the chimney above the Sistine Chapel, signalling that the cardinals had made their choice.
Dressed in his new white robes, the bespectacled Argentinian prelate looked pensive and a little nervous as he looked out at the thousands who had gathered in the rain on the piazza to see him.
Vatican officials reportedly offered Pope Francis an elaborate gold pectoral cross to wear around his neck before stepping onto the balcony but in a sign he will bring his own style to the papacy he told them he would prefer to keep the very simple cross that he had worn as a bishop.
Speaking to Premier's Marcus Jones during the News Hour from Rome, Premier's Maria Rodrigues-Toth said he seems to be shunning conformity:
British politicians and religious leaders have welcomed the new Pope.
In a statement the leader of Catholics in England and Wales Archbishop Vincent Nichols said: "As he begins his new Apostolic ministry, as the Bishop of Rome and Shepherd of the universal Church, Pope Francis may be assured of the prayers and loving support of the Catholic community throughout England and Wales."
Cardinal Cormac Murphy O'Connor said the Catholic Church had been "very blessed" by the election.
Cardinal on Pope Francis from Catholic Church (England/Wales) on Vimeo.
UK Prime Minister David Cameron said it was a "momentous day" for Catholics, while Archbishop of Canterbury Justin Welby, leader of the world's Anglicans, offered him "every blessing".
Argentina's President Christina Fernandez de Kirchner wished her fellow countryman a "fruitful pastoral mission" and expressed the hope that he will work toward justice, equality and peace for all.
US President Barack Obama offered warm wishes to the Pope and said the selection speaks to the strength and vitality of the Americas.
United Nations Secretary General Ban Ki-moon said he looked forward to co-operation under the Pope's wise leadership.
German Chancellor Angela Merkel said the hopes of "millions of believers in Germany and the world, now rest with the new Pope", while EU President Herman Van Rompuy and European Commission head Jose Manuel Barroso urged the pontiff to try to bring the world's people and religions closer together.
German Chancellor Angela Merkel said the hopes of "millions of believers in Germany and the world, now rest with the new Pope", while EU President Herman Van Rompuy and European Commission head Jose Manuel Barroso urged the pontiff to try to bring the world's people and religions closer together.
Stuart Windsor is a special ambassador for the anti-persecution charity Christian Solidarity Worldwide.
He tells Premier he hopes religious freedom will be high on the agenda of Pope Francis:
Pope Francis is known for his frugal lifestyle and being a champion for the poor.
As Archbishop he lived in a modest flat next to the Cathedral in Buenos Aires, where he cooked his own food rather than using servants.
And instead of being chauffeur driven he used the underground and local buses and when flying to Rome always flew economy class.
James Parker from the Catholic Bishops Conference in England and Wales has worked inside the Vatican and told Premier's News Hour that Pope Francis is a refreshing choice:
Pope Francis was born into a family of seven, his father an Italian immigrant railway worker and his mother a housewife.
He became a priest at 32, nearly a decade after losing a lung due to respiratory illness and quitting his chemistry studies.
Despite his late start, he was leading the local Jesuit community within four years.
He has a reputation as someone willing to challenge powerful interests and has had a sometimes difficult relationship with Argentine President Cristina Fernandez and her late husband and predecessor, Nestor Kirchner.
Displaying his conservative orthodoxy, he has spoken out strongly against gay marriage, denouncing it in 2010 as "an attempt to destroy God's plan", and is expected to pursue the uncompromising moral teachings of Benedict XVI and John Paul II.
He's the first Jesuit to become Pope. The order was founded in the 16th century to serve the papacy and is best known for its work in education and for the intellectual prowess of its members.
Ged Clapson's a spokesperson for the Jesuits in Britain. He gave Premier his reaction to the new Pope:
In a lighter moment, at a dinner after his election with the other cardinals, Pope Francis said, "May God forgive you," raising loud laughter, according to New York Cardinal Timothy Dolan.
"Habemus Papam Franciscum," was the first tweet by the papal account @pontifex since Benedict XVI stood down last month.
Pope Francis will be installed officially in an inauguration Mass at 8.30am UK time on Tuesday 19th March.