Pope Pius XII's decision to elevate the Apostolic Vicariate of the Hawaiian Islands to a diocese marked a turning point in the Roman Catholic Church's governance in Hawaii. The newly established Roman Catholic Diocese of Honolulu was a response to the expanding Catholic community throughout the islands, which required more structured leadership and local administration to meet the diverse needs of its congregants. The change allowed for the appointment of a bishop, enhancing the church's organizational framework and facilitating more direct pastoral oversight.

Prior to this elevation, the Catholic presence in Hawaii had been growing for several decades, chiefly due to European missionaries and later waves of immigrant Catholics from various countries. The decision from the Vatican underlined its commitment to the growth of the Catholic Church in the Pacific region and was part of a broader trend in which the church recognized the importance of local administration in its global mission.

Archbishop Francis James Spellman of New York was influential in this process as he advocated for the elevation during his tenure. The elevation also encompassed the educational and social justice missions of the church, reinforcing its role in providing spiritual, social, and educational support to island communities. As a result, the formation of the diocese fostered growth in parishes, schools, and charitable endeavors throughout Hawaii.