Joseph Connolly designed a building that was contemporary yet evoked Irish Roman Catholic church building traditions, which was important to the Irish priest and his predominantly Irish congregation at the time.

Connolly composed a three-aiselled basilica plan for the brick Gothic Revival design of St. Mary's Church, with a polygonal apsidal sanctuary, transepts slightly lower than the nave, and a morning chapel to the liturgical north or geographic south.
The tower is positioned in the centre of the main facade facing Bathurst Street.
Side portals and windows are enclosed within a large arch.

The main facade features a central section at the base of the tower with a rose window framed by a moulded pointed arch on columns and capitals, with recessed roundels located around the window.
Smaller and lower versions of this design symmetrically frame the middle section on both sides.
Beneath the central rose window is a blind arcade, and the main doorway below is topped with a gable with two roundels on either side.
The brick- and copper-clad spire is characterized by corner niches, with gables rising above belfry openings between the angle turrets.
The church's architecture aligns symmetrically with Adelaide Street with the tower facing the centre of the street, thus serving as a picturesque view terminus.
Connolly's Church of Our Lady Immaculate in Guelph, Ontario stands similarly at the head of that city's Macdonell Street.

Arches to the transepts are carried on piers inside, and acanthus capitals crown the stone columns of the main arcades.
The vaulted apse has a series of small stained-glass windows and paintings.
The altar is wide, and the church has a small reredos with statues of Jesus and the Blessed Virgin Mary.

The spire was completed in 1905 by architect Arthur W. Holmes, a former assistant of Connelly.
Joseph Connolly designed a building that was contemporary yet evoked Irish Roman Catholic church building traditions, which was important to the Irish priest and his predominantly Irish congregation at the time.
Connolly composed a three-aiselled basilica plan for the brick Gothic Revival design of St. Mary's Church, with a polygonal apsidal sanctuary, transepts slightly lower than the nave, and a morning chapel to the liturgical north or geographic south. The tower is positioned in the centre of the main facade facing Bathurst Street. Side portals and windows are enclosed within a large arch.
The main facade features a central section at the base of the tower with a rose window framed by a moulded pointed arch on columns and capitals, with recessed roundels located around the window. Smaller and lower versions of this design symmetrically frame the middle section on both sides. Beneath the central rose window is a blind arcade, and the main doorway below is topped with a gable with two roundels on either side. The brick- and copper-clad spire is characterized by corner niches, with gables rising above belfry openings between the angle turrets. The church's architecture aligns symmetrically with Adelaide Street with the tower facing the centre of the street, thus serving as a picturesque view terminus. Connolly's Church of Our Lady Immaculate in Guelph, Ontario stands similarly at the head of that city's Macdonell Street.
Arches to the transepts are carried on piers inside, and acanthus capitals crown the stone columns of the main arcades. The vaulted apse has a series of small stained-glass windows and paintings. The altar is wide, and the church has a small reredos with statues of Jesus and the Blessed Virgin Mary.
The spire was completed in 1905 by architect Arthur W. Holmes, a former assistant of Connelly.
St. Mary's Church, Toronto