Saint Teresa devoted her life to helping the destitute and the sick in slums in Kolkata.
Singing nuns and followers clutching flowers flocked to Mother Teresa's tomb in Kolkata to celebrate her proclamation as a saint at the Vatican later Sunday.
People started gathering from early morning at Mother House in Kolkata for a special mass for Mother Teresa ahead of the ceremony due at St Peter's Basilica.
They placed candles and flowers on her tomb in sombre contemplation, but the atmosphere at the headquarters of the Missionaries of Charity, the order that SaintTeresa founded, was also one of celebration.
Nuns were singing songs honouring her and giant television screens have been erected so the gathering visitors can watch the ceremony.
"It's a day of rejoicing, a day of gratitude and a day of many, many blessings," senior sister Mary Lysa said.
"The Missionaries of Charity has decided to turn this into a celebration to further mother's cause serving the poorest of the poor and the dying and sick."
"We will gather to witness the entire process at Vatican City as it unfolds," she said.
Saint Teresa devoted her life to helping the destitute and the sick in slums in Kolkata.
Lighting a candle and placing it on the tomb, Konica Cecilia said the beloved nun had given her impoverished parents money to help them send her to school as a child.
"I was fortunate to meet mother. She was a living saint and an inspiration to me," the 32-year-old said, adding that she was the pride of Kolkata.
"My memories of her comfort me when I am in trouble."
Sunday's ceremony comes one day short of the 19th anniversary of Saint Teresa's death, at 87, in Kolkata.
The Nobel Peace Prize winner's path to canonisation was sealed after the Vatican last year recognised the second of two required miracles, following her death.
But she had long been regarded as a living saint by many.
English literature teacher Madhura Banerjee described her as an inspiration to the younger generation in today's modern world.
"I was touched by her simplicity," said Ms Banerjee, who visited Saint Teresa in 1995 at the headquarters to celebrate her own birthday.
"When I think of her, it makes the difficult things look easy," she said.
At the various homes for the destitute in Kolkata run by the charity, celebrations were also taking place on Sunday, including serving special food for those in their care, Sister Lysa said.