He is the first pope from the Americas, the first Jesuit, and the first named Francis, after St. Francis of Assisi, the humble friar who dedicated his life to helping the poor. The last non-European pope was Syria's Gregory III from 731-41.
"You know that it was the duty of the Conclave to give Rome a Bishop," the new pontiff said as he waved shyly to the tens of thousands who braved a cold rain in St. Peter's Square. "It seems that my brother Cardinals have gone to the ends of the earth to get one ... but here we are.. . . I thank you for the welcome."
Bergoglio, said to have finished second when Pope Benedict XVI was elected in 2005, was chosen on just the fifth ballot to replace the first pontiff to resign in 600 years. In the last century, only Benedict, John Paul I in 1978, and Pius XII in 1939 were faster.
Francis' election elated Latin Americans, who number 40 percent of the world's Catholics but have long been underrepresented in the church leadership.
The new pontiff brings a common touch. The son of middle-class Italian immigrants, he denied himself the luxuries that previous cardinals in Buenos Aires enjoyed. He lived in a simple apartment, often rode the bus to work, cooked his own meals, and regularly visited slums that ring Argentina's capital.
He considers social outreach, rather than doctrinal battles, to be the essential business of the church.
"As a champion of the poor and the most vulnerable among us, he carries forth the message of love and compassion that has inspired the world for more than 2,000 years - that in each other, we see the face of God," President Obama said in a statement.
As the 266th pope, Francis inherits a church in turmoil, beset by the clerical sex-abuse scandal, internal divisions, and dwindling numbers in parts of the world where Christianity had been strong for centuries.
While Latin America still boasts the largest bloc of Catholics on a single continent, it has faced competition from aggressive evangelical churches that have chipped away at strongholds like Brazil, where the number of Catholics has dropped from 74 percent of the population in 2000 to 69 percent today.
Francis is sure to bring the church closer to the poverty-wracked region, while also introducing the world to a very different type of pope, whose first words were a simple "Brothers and sisters, good evening."
He asked for prayers for himself, and for Benedict, whose stunning resignation paved the way for his election.
"I want you to bless me," Francis said in his first appearance from the balcony of St. Peter's Basilica, asking the faithful to bow their heads in silent prayer.
Francis spoke by phone with Benedict, who has been living at the papal retreat in Castel Gandolfo, and told cardinals he plans to visit the retired pontiff on Friday, according to U.S. Cardinal Timothy Dolan. The visit was significant because Benedict's resignation has raised concerns about potential power conflicts emerging from the peculiar situation of having a reigning pope and a retired one.
Earlier Wednesday, shouts of joy went up from the throng huddled under a sea of umbrellas when plumes of white smoke poured out of the copper chimney atop the Sistine Chapel a few minutes past 7 p.m. local time. " Habemus Papam!" - "We have a pope!" - they chanted as the bells pealed in St. Peter's Basilica and churches across Rome.
After what seemed like an endless wait of more than an hour, they cheered again when the doors to the loggia opened and a cardinal stepped out and revealed the identity of the new pontiff, using his Latin name, then announced he would be called Francis.
In choosing to call himself Francis, the new pope was associating himself with the much-loved Italian saint from Assisi known as a symbol of peace, poverty, and simplicity.
St. Francis was born to a wealthy family but renounced his wealth and founded the Franciscan order of friars; he wandered about the countryside preaching to the people in very simple language.
He was so famed for his sanctity that he was canonized just two years after his death in 1226.
St. Francis Xavier is another important namesake. One of the 16th-century founders of the Jesuit order, Francis Xavier was a legendary missionary who spread the faith as far as India and Japan - giving the new pope's name further resonance in an age when the church is struggling to maintain its numbers.
In choosing Francis, the cardinals clearly decided that they didn't need a vigorous, young pope who would reign for decades but rather a seasoned, popular, and humble pastor who would draw followers to the faith and help rebuild a church stained by scandal.
Catholics are still buzzing over his speech last year accusing fellow church officials of hypocrisy for forgetting that Jesus Christ bathed lepers and ate with prostitutes.
In a lifetime of teaching and leading priests in Latin America, Bergoglio has also shown a keen political sensibility as well as the kind of self-effacing humility that fellow cardinals value highly, according to his official biographer, Sergio Rubin.
Bergoglio's legacy includes his efforts to repair the reputation of a church that lost many followers by failing to openly challenge Argentina's murderous 1976-83 dictatorship. His own record as the head of the Jesuit order in Argentina at the time has been tarnished as well.
Many Argentines remain angry over the church's acknowledged failure to openly confront a regime that was kidnapping and killing thousands of people as it sought to eliminate "subversive elements" in society. It is one reason why more than two-thirds of Argentines describe themselves as Catholic, but fewer than 10 percent regularly attend Mass.
Under Bergoglio's leadership, Argentina's bishops issued a collective apology in October 2012 for the church's failures to protect its flock. But the statement blamed the era's violence in roughly equal measure on both the junta and its enemies.
"Bergoglio has been very critical of human-rights violations during the dictatorship, but he has always also criticized the leftist guerrillas; he doesn't forget that side," Rubin said.
Bergoglio's own role in the "dirty war" has been the subject of controversy.
At least two court cases directly involved Bergoglio. One examined the torture of two of his Jesuit priests who were kidnapped in 1976 from the slums where they advocated liberation theology. One accused Bergoglio of effectively handing him over to the junta.
Both men were freed after Bergoglio took extraordinary, behind-the-scenes action to save them - including persuading dictator Jorge Videla's family priest to call in sick so that Bergoglio himself could say Mass in the junta leader's home, where he privately appealed for mercy. His intervention likely saved their lives, but Bergoglio never shared the details until Rubin interviewed him for a 2010 biography.
Rubin said that failing to challenge the dictators was simply pragmatic at a time when so many people were getting killed, and attributed Bergoglio's later reluctance to share his side of the story as a reflection of his humility.
Francis will celebrate his first Mass as pope in the Sistine Chapel on Thursday, and will be installed officially on Tuesday, according to the Rev. Federico Lombardi, the Vatican spokesman.
Vice President Biden will lead the U.S. delegation to the installation, according to a White House official who spoke on condition of anonymity.
One of Francis' first foreign trips is expected to be World Youth Day in Rio de Janeiro in July, an event that will likely energize the continent given their native son will be presiding.
Lombardi, also a Jesuit, said he was particularly stunned by the election given that Jesuits typically shun positions of authority in the church, instead offering their work in service to those in power.
But Lombardi said that in accepting the election, Francis must have felt it "a strong call to service," an antidote to all those who speculated that the papacy was about a search for power.
New York Cardinal Dolan gave an inside glimpse into the drama of the conclave, saying that when the tally reached the necessary 77 votes to make Bergoglio pope, the cardinals erupted in applause. And when he accepted the momentous responsibility thrust upon him, "there wasn't a dry eye in the place," the American cardinal recounted.
Later, the new pope shunned a special car and security detail provided to transport him to the Vatican hotel. He decided to stay with the cardinals.
" 'I'll just go with the guys on the bus,' " Dolan quoted him as saying.