The Roman Catholic Apostolic Prefecture of the Marshall Islands (Latin: Praefectura Apostolica Insularum Marshallensium) (MI) is an ecclesiastical territory below the rank of diocese, in the Republic of the Marshall Islands. The prefecture is a suffragan of the Metropolitan Province of Agaña. Although the see of the prefecture is not in the United States, the prelature does include Wake Island, which is an unorganized, unincorporated territory of the United States. The prefecture is led by a prefect who is pastor of the Cathedral of the Assumption in Majuro. The prefect was appointed from the local missionary Jesuits.
On April 23, 1993, Pope John Paul II split the former Diocese of Carolines-Marshalls into the Apostolic Prefecture of the Marshall Islands and the Diocese of Caroline Islands.
While small in total number of Catholics, the area covered is nearly the size of the United States.