The Roman Catholic Bishop of Dunedin, the Most Rev Colin Campbell, who attended the cannonisation in Rome, led the service.
The Bishop of Christchurch, the Most Rev Barry Jones, and Monsignor Bill Middleton, of Christchurch, also attended.
Little Sisters' Mother Superior Rose Chung said it was a very special occasion, as having their founder made a saint confirmed their mission to look after elderly people in need.
Worldwide, there are more than 2700 Little Sisters of the Poor who care for more than 13,000 elderly people in 202 homes.
The service also showed the gratitude the order had for its friends, benefactors and those who had helped with the celebrations, she said.