The Roman Catholic Archdiocese of Rosario (Latin: Archidioecesis Rosariensis) is an ecclesiastical territory or diocese of the Roman Catholic Church in the southern part of the province of Santa Fe, Argentina, with its mother church, the Basilica Cathedral of Our Lady of the Rosary, located in the city of Rosario.

The former archbishop Eduardo Mirás served as Apostolic Administrator of the Archdiocese between 22 December 2005 and 18 March 2006, the date that Msgr.

The diocese was created by Pope Pius XI through the bull Nobilis Argentinae Nationis Ecclesia on 20 April 1934, along with nine others, citing a lack of sufficient episcopal sees to attend to the population.

The first bishop was Antonio Caggiano, who was elevated to the episcopal dignity specifically for this post; at the time he was the General Counselor of the Argentine Catholic Action.

On 7 October 1966 (day of the Virgin of the Rosary), the pope named Rosario "City of Mary" and elevated the Cathedral to Basilica.