The new leader of the Catholic Church is the Argentine Cardinal Jorge Mario Bergoglio who has taken the name of Pope Francis.
Bergoglio, 76, is a Jesuit from Buenos Aires and is the first pope from South America. He is also the first pope to take the name of Francis.
The new pontiff stepped onto the Vatican balcony dressed in white to address the roaring crowd in St. Peter's Square where he humbly and calmly asked for the peoples' prayers.
"Let's pray always for each other. Let's pray for the whole world. May there be a great brotherhood," Pope Francis said in Italian.
He wished that the "voyage with the church that we begin today" be "successful in spreading the gospel."
A hush fell over the crowd when the pope said, "Let us pray silently in this prayer for me," and bowed his head.
Pope Francis recited the Lords' Prayer and the Hail Mary before making the sign of the cross to bless the crowd estimated to be more than 100,000 people.
"Brothers and sisters, I leave you. Thank you so much for the warm welcome. Pray for me and we'll see each other soon. Tomorrow I want to go pray to the Madonna. And I want to wish to all of Rome. Goodnight and good rest," Pope Francis said with a laugh and a wave before leaving the balcony among cheers and bells ringing.
The cardinals who elected the new pope looked out from surrounding balconies above the elated crowd.
French Cardinal Jean-Louis Tauran, the senior cardinal in the order of the deacons, stepped onto the balcony of St. Peter's Basilica to announce, "habemus papam," Latin for "We have a pope."
Tauran then revealed the pontiff's birth name and the name he has chosen for himself as pope.
Vatican spokesman Father Lombardi said Pope Francis called Pope Emeritus Benedict XVI and will probably meet with him soon. On Thursday, Pope Francis will say mass in the Sistine Chapel.
"I don't know what to say. I was completely in shock," Lombardi at a briefing in the Vatican press room. "I was taken by the election of a South American. The church there has been waiting."
Latin Americans are rejoicing at the selection.
"It's incredible!" Martha Ruiz, 60, told the Associated Press in Buenos Aires. A tearful Ruiz said that she has been in many meetings with the former cardinal. "He is a man who transmits great serenity."
"It's a huge gift for all of Latin America. We waited 20 centuries. It was worth the wait," Franciscan friar Jose Antonio Cruz told the AP in the Old San Juan district in Puerto Rico. "Everyone from Canada down to Patagonia is going to feel blessed. This is an event."
President Obama and Michelle Obama extended their well wishes to the new pontiff.
Obama said that the selection of the first pope from the Americas "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."
The appearance of the new pontiff triggered the second roar from more than 100,000 people jammed into St. Peter's Square. The first was when the faithful, standing in a cold rain, spotted white smoke wafting over the Vatican, signaling the election was over. Moments later the bells of St. Peter's Basilica rang out, soon joined by church bells all over Rome.
The election was over quickly, coming on the second day of the conclave. The Associated Press reported that the election was sealed on the fifth ballot.
The newly elected 266th pope was moved into the Room of Tears where he was outfitted with his new papal vestments before proceeding to a scarlet-draped balcony to greet the world's 1.2 billion Catholics watching around the world.
The Vatican band and Swiss Guard marched into St. Peter's Square ahead of the new leader who they have been sworn to protect for centuries.
Pope Francis will celebrate his installation mass on Tuesday at St. Peter's Basilica.
The 115 cardinal electors began the conclave on Tuesday following the resignation of Benedict XVI, the first pontiff to resign in 600 years. At least a two-thirds majority -- 77 votes -- was required to elect the next pope.
The new pope is then expected to step onto the balcony to greet the crowd gathered below in St. Peter's Square.