US Cardinal Robert Francis Prevost was elected in a surprise choice as the new leader of the Catholic Church on Thursday, taking the name Leo XIV, becoming the first American pontiff.

After white smoke billowed from a chimney atop the Sistine Chapel signifying that the 133 cardinal electors had chosen a new leader for the 1.4 billion-member Catholic Church, Pope Leo made an appearance on the central balcony of St. Peter's Basilica.

The choice of Prevost was announced by French Cardinal Dominique Mamberti with the Latin words "Habemus Papam" (We have a pope) to tens of thousands of people gathered in St. Peter's Square to hear the news.

Originally from Chicago, Prevost, 69, has spent most of his career as a missionary in Peru and became a cardinal only in 2023.

He has given very few media interviews and rarely speaks in public.

Leo becomes the 267th Catholic pope after the death of Pope Francis last month, who was the first Latin American pope and had led the Church for 12 years.

Pope Francis undertook a range of reforms and allowed debate on divisive issues such as women's ordination and better inclusion of LGBT Catholics.

Ahead of the conclave, some cardinals called for continuity with Francis' vision of greater openness and reform, while others said they wanted to go back and embrace old traditions.