Looking the picture of serenity, Pope Francis I stepped out onto the balcony and waved briefly before standing calmly above the cheering crowds.
He then led them in silent prayer before renewed cheering and bell-ringing.
Since Benedict XVI resigned, there was no mourning of a dead pontiff to mar the jubilant mood.
Bergoglio, 76, was believed to be the runner-up to Benedict XVI at the last conclave in 2005.
New pope elected