The fact that he chose a reformer's name was seen as a signal he might make great changes in the church. Like St. Francis of Assisi, Bergoglio has been known for his simplicity, humility and rejection of material comforts.
He is the first non-European pope in history, and is an Argentinean, though of Italian ancestry. He is known to oppose abortion and same-sex marriage, and has spent his entire career in Argentina. He is a member of the Jesuit order, sometimes known as the pope's "shock troops."
The White House released a statement in which U.S. President Barack Obama and first lady Michelle Obama, speaking on behalf of the American people, offered "warm wishes to His Holiness Pope Francis as he ascends to the Chair of Saint Peter and begins his papacy."
"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 two thousand years -- that in each other we see the face of God," Obama said. "As the first pope from the Americas, his selection also speaks to the strength and vitality of a region that is increasingly shaping our world, and alongside millions of Hispanic Americans, those of us in the United States share the joy of this historic day.
"Just as I appreciated our work with Pope Benedict XVI, I look forward to working with His Holiness to advance peace, security and dignity for our fellow human beings, regardless of their faith," the president said. "We join with people around the world in offering our prayers for the Holy Father as he begins the sacred work of leading the Catholic Church in our modern world."
The 76-year-old pope appeared on the balcony above a packed St. Peter's Square before more than 100,000 cheering people who braved cold and rainy weather.
"Dear brothers and sisters, good evening," the new pope told the crowd. "You know the duty of the conclave was to appoint a bishop of Rome and it seems to me that my brother cardinals have chosen one from far away. But here I am.
"I want to thank you for your embrace."
Francis asked the crowd to pray for his predecessor, Pope Emeritus Benedict XVI, who resigned last month.
After leading the crowd in the Our Father and Hail Mary, Francis said before he would bless the crowd he would ask members to bless him in silent prayer.
"Let us begin this journey together ... it is a journey of friendship, of love, of faith, of trust between us," Francis told the crowd.
"Let us pray for the whole world."
Francis said his blessing was "to you and to the world, to men and women of good will" and called on "the Holy Spirit to descend on you and remain with you always."
Before being introduced, the new pope was clad in his papal soutane in the "room of tears" behind the Sistine Chapel at the Vatican. The room is so named because new popes usually have been overcome with emotion.
Before the new pope's appearance, French Cardinal Jean-Louis Tauran declared "habemus papam," the formal Latin declaration meaning, "We have a new pope."
Bells rang out, crowds cheered and white smoke poured from the Sistine Chapel after the 115 cardinal electors chose the new pontiff in conclave.
Before the new pope's appearance on the balcony, Vatican security officers and papal orders, led by the Swiss Guard in steel helmets and uniforms designed by Michelangelo, trooped onto the steps of the basilica.
Francis will have to handle a variety of challenges, from pederast priests to Vatican Bank scandals to allegations of a homosexual clique within the Vatican bureaucracy.
His selection occurred on the second day of the conclave, on the fourth vote.