The canonisation date has been set by Pope Francis after he approved a second miracle attributed to Mother Teresa's intercession in December.
Her sainthood date falls on the eve of the 19th anniversary of her death.
The nun cared for the poorest of the poor and will now become the centrepiece of the pontiff's year-long focus on the Catholic Church's merciful side.
She was an Albanian nun who won the Nobel Peace prize in 1979, and is best known for her work among the impoverished in the slums of Kolkata (formerly Calcutta), India.
Pope Francis approved the healing of a Brazilian man with brain tumours who prayed to Mother Teresa.
The Pope met Mother Teresa in 1994 at a Vatican synod.
Vatican spokesman Fr Federico Lombardi said the Pope, then the Archbishop Jorge Mario Bergoglio, developed a great esteem for her: "He heard her intervene often with great strength, without letting herself in any way be intimidated by an assembly of bishops.
"And from that he developed a great esteem for her, as a strong woman, a woman able to give courageous testimony."
In Catholicism, two miracles are needed to become a saint.
The Vatican recognised Mother Teresa's first miracle in 2002, a healing of a Bengali tribal woman with an abdominal tumour.
She was beatified by Pope John Paul II in 2003, the first step to being canonised.
