St. Mary’s was originally located on Waterloo Street in Saint John. The building was consecrated on Ascension Day, May 9th, 1861. It was built to meet the needs of the heavily populated area around Haymarket Square. Many of the people living in the area worked in the shipbuilding industry for years which lined the shoreline at that time. It was not uncommon to find four or more families living in large tenements in the area. From the outset, St. Mary’s was built as a “free church,” accessible to the poor and depending solely for its support on the free-will offering of its congregation, rather than on the money raised from pew rentals.
In 1966, representatives of the Saint John General Hospital which occupied the property next to St. Mary’s, made an offer to purchase the buildings and associated property, to facilitate the expansion of the hospital.
St. Mary's amalgamated with St. Bartholomew's (Rothesay Ave., Coldbrook, opened 1917) in a new building in Forest Hills effective on October 1st, 1967.