Pope Leo XIV made an unannounced visit to Rome's Basilica of St Mary Major, where he could pay respects to the late Pope Francis, who is buried at the church.
The white-robed American pope kneeled before Francis's simple marble tomb in the basilica beloved of the Argentine pontiff, who died on 21 April.
In a short statement, the Vatican's press office said Pope Leo also prayed to the icon of the Virgin Mary at the basilica.
He waved from the passenger side of a Volkswagen vehicle as he arrived at the basilica.
He was coming from the small town of Genazzano, where he had earlier visited a shrine dedicated to the Virgin Mary.
The new pope has signaled that he would continue with the vision and reforms of Pope Francis, telling the world's Catholic cardinals the late pontiff left a "precious legacy" that they must continue.
In his first meeting with all the cardinals since his election as pontiff, Pope Leo also asked the senior clerics to renew their commitment to major church reforms enacted by the landmark Second Vatican Council in the 1960s.
Pope Leo said that Francis, who died on 21 April and broadly had a vision of opening the staid 1.4-billion-member church to the modern world, had left an "example of complete dedication to service".
"Let us take up this precious legacy and continue on the journey," the new pope instructed the cardinals.
The pontiff also asked the clerics to "renew together our complete commitment" to the reforms enacted by the council, which included celebrating the Mass in local languages rather than Latin and pursuing dialogue with other religions.
He cited Francis' focus on "courageous and trusting dialogue with the contemporary world in its various components and realities".
Read: From one Pope to another - what changes will be made?
Pope Leo also told cardinals his choice of name reflects a commitment to social causes embraced by Leo XIII, who defended workers' rights, according to the Vatican.
"I chose to take the name Leo XIV," he said in a transcript of a speech published by the Vatican, because the 19th-century pontiff "addressed the social question in the context of the first great Industrial Revolution".
He added that today, social teaching is needed "in response to another Industrial Revolution and to developments in the field of artificial intelligence that pose new challenges for the defence of human dignity, justice and labour".
The US-born Robert Francis Prevost celebrated his first mass as Pope Leo yesterday morning in the Sistine Chapel, where he was elected by fellow cardinals on Thursday evening.
The mass was private, attended by red-hatted cardinals of all ages, not just those under 80 who were eligible to vote in the conclave.
In his homily, broadcast live by the Vatican, the 69-year-old said the Church could be a "beacon" to reach areas suffering a lack of faith, which focus on "technology, money, success, power or pleasure".
He will make his second public appearance tomorrow at 11am Irish time, delivering a prayer from the window of the Apostolic Palace overlooking St Peter's Square.
