Pope Leo XIV formally began his reign on Sunday by reaching out to conservatives who felt orphaned under his predecessor, calling for unity, vowing to preserve the Catholic Church's heritage and not rule like "an autocrat".
After a first ride in the popemobile before tens of thousands of people in St Peter's Square, Leo was formally installed as the 267th pontiff of the Roman Catholic Church and sovereign monarch of Vatican City at an outdoor Mass.
Well-wishers in the crowd waved US and Peruvian flags, with people from both countries claiming him as the first pope from their nations.
The open-topped popemobile was surrounded by more than a dozen security guards as it drove through the square and down the long boulevard that leads to the Tiber River, for Pope Leo's first ride. Source: AP / Andrew Medichini
Crowds chanted "Viva il Papa" (Long Live the Pope) and "Papa Leone", his name in Italian, as his distinctive, open-topped popemobile weaved around St Peter's Square.
The vehicle moved quickly, but briefly stopped twice so Leo could bless three babies. Source: AP / Andrew Medichini
Francis, an Argentine, died on 21 April after leading the Church for 12 often turbulent years during which he battled with traditionalists and championed the poor and marginalised.
Italian authorities deployed thousands of security officers for the event, alongside snipers on rooftops and anti-drone operations. Source: Getty / Picture Alliance
Saying he was taking up his mission "with fear and trembling", Leo used the words "unity" or "united" seven times and the word "harmony" four times.
"It is never a question of capturing others by force, by religious propaganda or by means of power. Instead, it is always and only a question of loving, as Jesus did," he said, in apparent reference to a war of words between Catholics who define themselves as conservative or progressive.
"Brothers and sisters, I would like that our first great desire be for a united Church, a sign of unity and communion, which becomes a leaven for a reconciled world," he said.
Referring to St Peter, the 1st century Christian apostle from whom popes derive their authority, Leo said: "Peter must shepherd the flock without ever yielding to the temptation to be an autocrat, lording it over those entrusted to him. On the contrary, he is called to serve the faith of his brothers and sisters, and to walk alongside them."
US Vice President JD Vance, a Catholic convert who clashed with Francis over the Trump administration's hard-line immigration policies, led a US delegation alongside Secretary of State Marco Rubio, who is also Catholic.
US Vice President JD Vance briefly shook hands with Ukrainian President Volodymyr Zelenskyy at the start of the inauguration ceremony. Zelenskyy last met Vance in February in the White House, when the two men clashed fiercely in front of the world's media. Source: AP / Gregorio Borgia
He is expected to raise efforts to free Melbourne teacher Oscar Jenkins from Russian custody with his Ukrainian counterpart.
Many other world leaders attended the ceremony, including the presidents of Peru, Israel and Nigeria, the prime ministers of Italy, Canada and Australia, German Chancellor Friedrich Merz and European Commission President Ursula von der Leyen.
European royals also took their place in the VIP seats near the main altar, including Spanish King Felipe and Queen Letizia.
As part of the ceremony, Leo received two symbolic items: a liturgical vestment known as a pallium, a sash of lambswool representing his role as a shepherd, and the "fisherman's ring", recalling the first pope, St Peter, who was a fisherman.
The ceremonial gold signet ring is specially cast for each new pope and can be used by Leo to seal documents, although this purpose has fallen out of use in modern times.
It shows St Peter holding the keys to Heaven and will be broken after his death or resignation.
