The Roman Catholic Diocese of Marquette is an ecclesiastical territory of the Catholic Church, encompassing the Upper Peninsula region of Michigan in the United States. The diocese is a suffragan diocese in the ecclesiastical province of the metropolitan Archdiocese of Detroit. Its cathedral is St. Peter Cathedral in Marquette, which replaced Holy Name of Mary Pro-Cathedral at Sault Ste. Marie.

The Archdiocese of Detroit is a Latin Church ecclesiastical territory or archdiocese of the Catholic Church covering the Michigan counties of Lapeer, Macomb, Monroe, Oakland, St. Clair, and Wayne. It is the metropolitan archdiocese of the Ecclesiastical Province of Detroit, which includes all dioceses in the state of Michigan. In addition, in 2000 the archdiocese accepted pastoral responsibility for the Catholic Church in the Cayman Islands, which consists of Saint Ignatius Parish on Grand Cayman.