| By Frances Kennedy |
BBC News, Rome
Sister Alphonsa (1910-1946) of Kerala was beatified in 1986 by the late Pope John Paul II on a visit to India. She will be formally canonised in October.
She had burnt and disfigured herself to avoid a marriage, having chosen to dedicate her life to Christ.
She will become a saint ahead of the Albanian nun Mother Teresa of Calcutta.
Mother Teresa was beatified in 2003.
The decision to accord sainthood to Sister Alphonsa was made over the weekend at a meeting between the Pope and other cardinals at the Vatican.
Sister Alphonsa, whose real name was Anna Muttathupadathu, was described by those who knew her as generous and loving.
She persisted with her religious vocation despite serious health problems, and in 1928, she was ordained, taking the name Sister Alphonsa.
Father Bernard J O'Connor of the Vatican's Congregation of Eastern Churches told the BBC News website he had recently visited India and met many people who fondly remembered Sister Alphonsa.
"Catholics but also non-Catholics and even non-Christians were speaking about her, showing me her pictures and telling me they had image in their homes," Father O'Connor said.
"I think she is a symbol of a kind of religious sensitivity and charity that touches ordinary peoples' lives" he added.
After Sister Alphonsa's death, local people in Kerala attributed miracles to her.
Her burial place at Bharananganam in southern Kerala, has become a pilgrimage site.
The beatification process examined the miracle whereby a young paralysed boy was miraculously cured of his ailment due to her prayers.
As well as being the fully Indian saint - Gonsalo Garcia, declared a saint by the church in the 17th century, had a Portuguese mother - Sister Alphonsa is the first representative from the Kerala church to attain such honour within the Catholic Church.
The Kerala church traces its origins to the visit of St Thomas around 2,000 years ago to preach the gospel in India.
The news that a date had been set for Sister Alphonsa's canonisation was greeted with joy by her order - the Congregation of Poor Clares of the Third Order of St Francis, also known as Clarists.
The order is known for working with poor, indigenous people of all classes and religions.
'Source of pride'
Marco Tosatti, Vatican correspondent for Italian daily La Stampa, said the canonisation would be offer support to Christians in India "who are often subject of persecution and violence by some Hindu groups, for political motives".
Having a 100% Indian saint, Mr Tosatti added, is "a source of pride and shows that Christianity is now deeply rooted in India - it is not something that comes from outside".
Indian Christians have been accused by hardline Hindu nationalists of "forced conversions" - especially among low-caste and tribal peoples.
They are also accused of making conversion to Christianity a condition for receiving treatment at medical centres they run.
Christians argue that low-caste and tribal people often convert willingly because of their treatment as outcasts.
The state of Orissa, which is mainly Hindu and has a tiny Christian minority, saw violence between the two communities erupt in December.
Local Christians were chased out of several churches - often just mud huts with thatched roofs - which were then set alight.
The people behind the attack said they were responding to a Christian attack on a Hindu religious leader.
Orissa has a law obliging people to ask for police permission before changing religion - thought to be a measure aimed at curbing Christian missionaries.