Argentine Cardinal Jorge Bergoglio has been elected by his peers as the new pope, becoming the first pontiff from the Americas.
He has chosen to be known as Pope Francis.
White smoke billowed from the Vatican's Sistine Chapel earlier Wednesday, indicating the cardinals selected Francis after two days of voting.
The voting came after Benedict XVI stunned the Catholic world last month by becoming the first pope in 600 years to resign. Crowds packing St. Peter's Square were seen waving flags and were cheering the announcement as bells were ringing.
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.
Francis became the winner after receiving at least 77 votes, which is more than two thirds of the cardinals.
Congratulations, Pope Francis I!