Pope Leo officially recognized 15-year-old London-born teenager Carlo Acutis as the first millennial saint during a large open-air Mass held on Sunday, September 7 in St.peter's Square at the Vatican.
Carlo, who passed away from leukemia in Milan in 2006, made websites to share Catholic teaching which led to him being called "God's influencer."
Around 80,000 people attended the outdoor Mass including many millennials and families with young children.
The Vatican announced that 36 cardinals, 270 bishops and hundred of priests participated in the Mass.
At the same time, Leo also declared Pier Giorgio Frassati, another well-known Italian who died at a young age, a saint.
Leo praised both men for living remarkable lives devoted to God, calling them as "masterpieces."
After completing all the steps required for sainthood, Carlo canonization was first scheduled for April 27, but it was delayed because of Pope Francis’ death.
In 2020, Pope Francis acknowledged a miracle connected to Carlo, giving him the tittle "blessed," after 7-year-old Brazillian boy named Matheus Vianna was cured of a rare pancreatic illness following contact with one of Carlo's T-shirts.
A second miracle was recognized last year when Costa Rican student Valeria Valverde completely recovered from serious head injuries from a bicycle incident after her mother prayed at Carlo's tomb.
In the past year, more than a million people went to Assisi, Italy to see Carlo's body displayed in a glass case at Santa Maria Maggiore church, dressed in his casual clothes with a wax covering his face while his heart is kept in a golden casket at San Rudina cathedral.