Vatican City: The Vatican has announced that American Cardinal Robert Francis Prevost will lead the Catholic Church as Pope Leo XIV.
Leo XIV becomes the first-ever US pope.
According to the Italian news agency Ansa, the new pope was elected in the fourth round of voting.
The conclave of 133 cardinals to elect the successor to the late Pope Francis began early Wednesday evening.
There was one unsuccessful ballot on Wednesday. Three more ballots were held on Thursday. A two-thirds majority is required.
For most of the past century, the conclave took between three and 14 ballots to elect a pope.
John Paul I, the pope who reigned for 33 days in 1978, was elected on the fourth ballot. His successor, John Paul II, took eight. Francis was elected on the fifth ballot in 2013.
Pope Leo XIV makes first address
Pope Leo XIV has made his first address to the world's 1.4 billion Catholics from the balcony of St. Peter's Basilica.
"Peace be with you all," Leo XIV told the crowd that had gathered at the Vatican.
Leo XIV said he was an Augustinian priest, but added that he was above all a Christian, and a bishop.
"So we can all walk together," he said.
The newly-elected pontiff urged people to "build bridges through dialogue, through encounter, to come together as one people, always in peace."
He also payed homage to his predecessor, the late Pope Francis.
Leo XIV addressed the crowed first in Italian before switching to Spanish, recalling the many years he spent as a missionary in Peru where he eventually became bishop of Chiclayo.
The 66-year-old US cardinal is the Catholic Church's first leader from North America in its 2,000-year history.
St. Peter's Square erupts with joyous applause
Thousands of Catholics as well as curious onlookers in St Peter's Square cheered and applauded as white smoke billowed from the Sistine Chapel, signalling the election of a new pope.
People had gathered from around the world since the conclave began Wednesday.
The crowd shouted "Hallelujah!" and "Viva il papa!" upon seeing the news that a pope had been elected.
"It's an amazing feeling," said one onlooker who had traveled from Belfast to Rome for the occasion.
"I'm not an overly religious person but, being here with all these people just blew me away," they told the AFP news agency.
Among the cardinals who were considered key contenders to be the next pope were representatives from Europe, Africa and Asia.