The chapel has often been referred to as "The Heart of St. Annís". For the Sisters, their lives as Postulants and Novices began in the chapel, and ended there, when they passed away. For students, it was a place of beauty and music, that put them on their best behaviour. Many of the girls received their first Holy Communion there. The chapel became part of St. Annís in 1886, when it was added on to the newly built wing of the school and Convent. However, the history of the chapel begins long before that date.
A chapel for daily use was built into the 1871 wing of the school, on the second floor, consisting of one main room, with pocket doors to allow for the inclusion of the adjacent rooms when extra space was needed. In 1886, the Sisters of St. Ann received, as a gift, St. Andrewís, the wooden Roman Catholic Cathedral which sat just across the street from the Convent, and had it moved, on skids, over to their side. It was to serve as the place of worship for their religious community, as the Catholic congregation planned to construct a larger cathedral. As well, the construction of a hospital on the site threatened the little church with demolition.