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. Fr. Sanborn is eminently qualified to form young men for the priesthood. He has a profound grasp of Thomistic philosophy and of Catholic dogmatic and moral theology, and is an outstanding teacher who is able to communicate his knowledge effectively. In addition to expertise in Latin and a working knowledge of Greek, German and Spanish, he is fluent in French and Italian, and has a broad understanding of Catholic history and culture. He is devoted to the solemnities of the sacred liturgy, and his years as a priest and seminary rector provided him with many insights into priestly spirituality.
In 1999 Fr. Sanborn began teaching the seminarians a course on the history of modern errors. It was the product of several years of reading and research, and will one day be published as a book.
In June, 2002, he was consecrated a bishop by the Most Rev. Robert F. McKenna, OP.