Niederauer was ordained to the priesthood on April 30, 1962. He was raised to the rank of Honorary Prelate of His Holiness in 1984. Niederauer served as Rector of St. John’s Seminary in Camarillo from 1987 to 1992. He was appointed the eighth Bishop of Salt Lake City by Pope John Paul II on November 3, 1994. Niederauer received his episcopal consecration on January 25, 1995 from Cardinal Roger Mahony, with Archbishop William Levada and Bishop Tod David Brown serving as co-consecrators. As bishop he was seen as "the most approachable of persons and one whose homilies were almost magical in their ability to make potentially difficult Scripture passages and theological concepts comprehensible and applicable – even inspiring – in our daily lives."