Mother Teresa, the Catholic nun who worked on behalf of the poor in the Indian city of Kolkata for a half-century, was declared a saint by Pope Francis on Sunday.
Nineteen years after her death at the age of 87, the title was given to Teresa in a ceremony in St Peter's Square attended by hundreds of thousands of admirers.
The open-air Mass for Teresa was a high point of the pope's Holy Year of Mercy, which ends in November.
"Mother Teresa, throughout her life, was a generous dispenser of divine mercy," the pope told the cheering crowd. "To the whole world of volunteers: may she be your model of holiness," he continued.
"She attended to the weary who were allowed to die on the roadside because she recognized the dignity God had given them. She raised her voice against the world's powerful, so that they would recognize their guilt for the crime of poverty that they created," Francis said.
Meanwhile special prayer ceremonies and events were being held across India to celebrate the nun's elevation as a saint, with hundreds gathering at the headquarters of the Roman Catholic missionary founded by the iconic missionary nun.
President Mukherjee called Mother Teresa a "messiah of the poor and a pillar of support for the weak and suffering," adding that every Indian will take pride in her canonization.
Born Agnes Gonxha Bojaxhiu in 1910, in Skopje, Macedonia, the ethnic Albanian Teresa became an icon of the 20th century through her service to India's most destitute.
In 1950, she got permission to open her own order in Kolkata, the Missionaries of Charity, with the purpose of caring for those who had no one to look after them.
Nuns of her order, with their trademark blue-bordered, white saris, picked up abandoned children from the streets, cleaned the wounds of lepers and tended to the mentally ill.
Today the order has 4,500 members and runs homes for the homeless in 133 countries.
"The loneliest, the most wretched and the dying have, at her hands, received compassion without condescension, based on reverence for man," the Nobel committee said in 1979, as it awarded her the Nobel Peace Prize.
The Vatican recognized her sainthood after attributing two "miracles" to her: the curing of an Indian tribal woman from stomach tumour in 1998, and the healing of a Brazilian man from several brain tumours 10 years later.
She also received a fair share of criticism: over medical neglect at the homes for the dying, over religious fundamentalism, over baptizing the dying without consulting them, over taking money from dictators and over financial irregularities as her order grew.
But for most people, especially in India where she chose to live and work, Teresa was loved and revered, often referred to as the "Angel of the Poor" and "Saint of the Gutter."
Teresa's path to sainthood was one of the fastest in the history of the Catholic Church. She was beatified by Pope John Paul II and given the title Blessed Teresa of Kolkata in 2003.
The pope invited 1,500 homeless people for pizza after the ceremony, Vatican Radio reported, citing the office of the pope.
Many of the homeless are living in shelters established by Teresa's Missionaries of Charity and were give a special welcome at the celebration on St Peter's Square.
The pizza is to be is to be baked by a team of chefs from Naples and served by more than 250 nuns from Teresa's missionaries, according to the report.