The Duke of Edinburgh will travel to the Vatican on behalf of the royal family for the new Pope's formal installation as pontiff at a mass in St Peter's Square on May 18.
Edward, the King's brother, will be joined by global leaders for the ceremony to mark the official start of Pope Leo XIV's tenure as head of the Catholic Church.
King Charles sent a private message to the Pope congratulating him on his election as he expressed "most sincere good wishes for his Pontificate".
The new pontiff, who was formerly known as Robert Prevost, is the first American-born Pope in history and called for the Catholic Church to "desperately" try to remedy a lack of faith in his first mass at the Vatican on Friday.
"A lack of faith is often tragically accompanied by the loss of meaning in life, the neglect of mercy, appalling violations of human dignity, the crisis of the family and so many other wounds that afflict our society," Leo said in an address delivered in Italian.
The pontiff warned that people have been turning away from the church in favour of "technology, money, success, power, or pleasure".
He also echoed the calls of his predecessor, the late Pope Francis, in calling for peace around the world.
"Help us, and each other, to build bridges through dialogue, through encounter, to come together as one people, always in peace," he said.
Prince William had attended the funeral of Pope Francis on behalf of the King in April after his death at the age of 88.
Charles, who had met the late pontiff with his wife Queen Camilla just weeks before Francis's death, had issued a statement paying tribute to the late pontiff.
"My wife and I were most deeply saddened to learn of the death of Pope Francis. Our heavy hearts have been somewhat eased, however, to know that His Holiness was able to share an Easter Greeting with the Church and the world he served with such devotion throughout his life and ministry," the King wrote.
Charles recalled Francis's compassion and tireless commitment to the faith, saying he had touched the lives of many.Â
"We send our most heartfelt condolences and profound sympathy to the Church he served with such resolve and to the countless people around the world who, inspired by his life, will be mourning the devastating loss of this faithful follower of Jesus Christ. Charles R."
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