The Diocese of Rockford was established on September 23, 1908, by Pope Pius X as a division of the Archdiocese of Chicago. The first Bishop was the Right Reverend Peter James Muldoon, installed on December 15, 1908. The Rockford Diocese serves 11 counties in northern Illinois, encompassing a vibrant and diverse Catholic community.

There are currently 105 parishes and 6 missions within the Diocese, with the historic Cathedral of St. Peter, consecrated in 1925, serving as the spiritual heart. The Diocese of Rockford has flourished through the dedicated leadership of its Bishops and the faith and commitment of its clergy, religious, and parishioners.

Bishop David J. Malloy became the ninth Bishop of the Diocese of Rockford on May 14, 2012, continuing the mission of fostering faith and serving the community with compassion and unity.