Father Van der Bom and Dr. Benjamin B. Ross organized St. Mary's Hospital, which was staffed by four Daughters of Charity of St. Vincent de Paul, in 1874.

In 1886 the Polish families of the parish established Holy Rosary Mission in East Saginaw.

[4] The Sisters of Providence left St. Mary's Academy in 1907 and deeded the property to the Bishop of Grand Rapids.

St. Mary's Church became the cathedral of the Diocese of Saginaw when it was established by Pope Pius XI on February 26, 1938.

A Blessed Sacrament chapel was created, movable chairs replaced the pews, the gallery was expanded, the organ and choir area were relocated, a new side entrance from the parking lot was created, and the interior was redecorated and painted.

[8] Because of declining enrollment and increased tuition, the East Side Catholic Schools system was created in 1982.

In January 2007 Bishop Robert J. Carlson formed a diocesan committee to study the possibility of renovating and renewing the Cathedral campus.

Neighborhood Renewal Services helped the diocese purchase back the former cathedral school building in September of the same year.

The following month the diocese bought the former convent from Holy Cross Children's Services, which was in the process of relocating.

The $4.7 million renovation included a re-configuration of the interior; a new marble altar, ambo, and baptismal font; new wooden cathedra and pews; and an addition that contains handicapped accessible restrooms.