In 1930, he accepted the call to serve as rector of St. John's-by-the-Sea Reformed Episcopal Church in Ventnor City, New Jersey.
Culbertson was elected bishop of the New York City and Philadelphia Synod of his denomination in 1937 and served in that position until he assumed the duties as dean of Moody Bible Institute in Chicago, Illinois, in 1942.
Missionary technical courses, including aviation and radio, were also added to the curriculum.
Culbertson died on November 16, 1971, at the Swedish Covenant Hospital in Chicago, Illinois.
Warren W. Wiersbe wrote his biography, William Culbertson: A Man of God, by Moody Press.