Donald J. Sanborn was born in New York, where he attended Catholic elementary school and high school. In 1967 he entered the seminary college for the Diocese of Brooklyn, where he majored in classical languages and graduated cum laude in 1971.

That same year, unhappy with the modernist seminary training he was receiving, he entered Archbishop Marcel Lefebvre’s seminary in Ecône, Switzerland, thus becoming one of the first seminarians in the newly founded Society of St. Pius X (SSPX).

Donald Sanborn was ordained a priest by Archbishop Lefebvre on June 29, 1975. He returned to East Meadow, on New York’s Long Island, to assist the Rev. Clarence Kelly. He taught at St. Pius V School on Long Island, and traveled to offer Mass in Pennsylvania, Delaware and Virginia.

In January 1977 Archbishop Lefebvre appointed him rector of St. Joseph’s House of Studies in Armada, Michigan, SSPX’s first American seminary. In fall of that year, he was joined by the Rev. Anthony Cekada. The following year he acquired a church facility in Redford, Michigan, to serve Catholics in the Detroit metropolitan area.

From Armada, Fr. Sanborn conducted an extensive search throughout the United States for a new and larger seminary facility to accommodate the growing number of seminarians. In 1979, with the consent of Archbishop Lefevbre, he acquired a former Jesuit retreat house in Ridgefield, Connecticut, which was then renamed St. Thomas Aquinas Seminary and became the new home of SSPX’s U.S. seminary.

He immediately made plans for the expansion of the Ridgefield facility, and launched a major fundraising program, which by 1982 allowed construction to begin on a new wing.

In April 1983 he was among the nine American priests expelled from SSPX because they objected to liturgical changes imposed by Archbishop Lefebvre, as well as to other disturbing leftward trends in the Archbishop’s organization. Thereafter in 1984 Fr. Sanborn established Blessed Sacrament Chapel in Martinez, California.

After returning to Michigan in 1986, he acquired a large school complex in Warren, a northeast suburb of Detroit. This became the home for Mary Help of Christians Academy, and for Queen of Martyrs Chapel, which in 1999 would later acquire a large church in Fraser, another northeast suburb.

In 1991 he founded Sacerdotium, a scholarly quarterly for traditional Catholic priests, and Catholic Restoration, a periodical for the Catholic laity. Both immediately acquired a well-deserved reputation for excellence in content and presentation.

During this period, Fr. Sanborn turned his attention to writing, and produced a series of articles analyzing the errors of Vatican II and John Paul II.

In 1995, with the encouragement of fellow traditional Catholic priests, he founded Most Holy Trinity Seminary in Florida. All the seminary’s graduates were ordained by Bishop Dolan, who was consecrated a bishop in 1993, until Fr. Sanborn was consecrated a bishop in June, 2002 by the Most Rev. Robert F. McKenna, OP.

During this time, Bishop Sanborn also served as pastor of the Queen of All Saints Chapel in Brooksville, Florida.

On February 22, 2018, Bishop Sanborn consecrated his intended successor, Fr. Joseph Selway, as a bishop, with Bishop Geert Stuyver and Bishop Daniel Dolan assisting as co-consecrators.

Currently Bishop Sanborn serves as the rector of Most Holy Trinity Seminary, which was relocated to Reading, Pennsylvania in the fall of 2022.