After announcing "Habemus Papum" - "We have a pope!" - a cardinal standing on the balcony of St. Peter's Basilica on Wednesday revealed the identity of the new pontiff, using his Latin name.
Bergoglio had reportedly finished second in the 2005 conclave that produced Benedict XVI - who last month became the first pope to resign in 600 years.
The 76-year-old archbishop of Buenos Aires has spent nearly his entire career at home in Argentina, overseeing churches and shoe-leather priests.
Tens of thousands of people who braved cold rain to watch the smokestack atop the Sistine Chapel jumped in joy when white smoke poured out a few minutes past 7 p.m., many shouting "Habemus Papam!" or "We have a pope!" - as the bells of St. Peter's Basilica and churches across Rome pealed.
Chants of "Long live the pope!" arose from the throngs of faithful, many with tears in their eyes. Crowds went wild as the Vatican and Italian military bands marched through the square and up the steps of the basilica, followed by Swiss Guards in silver helmets and full regalia.
They played the introduction to the Vatican and Italian anthems and the crowd, which numbered at least 50,000, joined in, waving flags from countries around the world.