On November 15, 1980, Fr. Nathaniel was consecrated Bishop of Dearborn Heights, as an auxiliary bishop to Archbishop Valerian Trifa. He served as Bishop until 1984, when Abp. Valerian retired. On November 17, 1984, Bishop Nathaniel became the ruling hierarch of the Romanian Orthodox Episcopate of America; on October 20, 1999, the Holy Synod of the OCA elevated him to the rank of Archbishop.