[1] Bishop Thomas Louis Connolly had arrived in Saint John in 1852 and needed to make a place of worship which would accommodate the large Irish Catholic population.

Realizing that the Catholic population required a larger facility, Bishop Connolly on November 14, 1852, announced to the congregation his intention to proceed immediately with the erection of the cathedral.

Plans were subsequently prepared in New York City during the winter of 1852–53, the foundation stone was laid in May 1853 and walls were erected, with the roof built by November 1853.

The bells were part of a larger set cast in 1884 especially for the World's Industrial and Centennial Cotton Exposition at New Orleans, where they were awarded a gold medal.

A statue of Our Lady of Immaculate Conception, Patroness of the cathedral is set up in a Gothic shrine offsetting the pulpit of similar design on the opposite pillar.