The Diocese of Columbus contains 108 parishes in 23 counties: Coshocton, Delaware, Fairfield, Fayette, Franklin, Hardin, Hocking, Holmes, Jackson, Knox, Licking, Madison, Marion, Morrow, Muskingum, Perry, Pickaway, Pike, Ross, Scioto, Tuscarawas, Union, and Vinton.

After the American Revolution ended in 1783, Pope Pius VI erected in 1784 the Prefecture Apostolic of the United States, encompassing the entire territory of the new nation.

The first Catholic chapel built in Ohio was a log structure in Perry County; it was dedicated in 1818 by Edward Fenwick.

[5] The visit of Cincinnati Bishop John Purcell to central Ohio in June 1836, began the activity of the Catholic Church in the city of Columbus.

After saying Mass in a house on Canal Street on June 5, Purcell asked the Catholic men in attendance to meet regarding the construction of a church.

[4] At the close of the Second Plenary Council of Baltimore in 1866, the American bishops petitioned Pope Pius IX to establish a new diocese with its seat in Columbus.

The diocese was mostly agricultural, having been settled first by Maryland and Pennsylvania residents who had moved west, and then later by German and Irish immigrants.

Rosecrans established the Catholic Columbian, a newspaper for the diocese, in addition to opening St. Aloysius Seminary and St. Vincent's Orphan Asylum.

During his 19-year-long tenure, Watterson increased the number of priests and schools in the diocese, oversaw the building of two hospitals and the Pontifical College Josephinum in Columbus and erected many new missions and parishes.

[7] On April 6, 1900, Henry K. Moeller, chancellor of the Archdiocese of Cincinnati, was appointed the third bishop of Columbus by Leo XIII.

Moeller also established missions, parishes, and schools to serve the increasing immigrant population of the Diocese.

During his tenure, Hartley oversaw a significant growth of the diocese In 1905, he erected his first parishes, Holy Rosary and St. Aloysius.

He established the Clergy Advisory Council, and oversaw the renovation of St. Joseph's Cathedral after issuing regulations for liturgical changes.

[24][25] In 2005, Campbell proposed the establishment of a civil registry of priests from the diocese of Columbus who had been "credibly accused" of sexual abuse.

[26] Campbell spoke out in 2006 against a proposed law in the Ohio General Assembly that would have allowed a 20-year statute of limitations for sexual abuse cases.

In his testimony to the legislature, Campbell claimed that the 20-year window for prosecution wasn't fair and would curtail the church's charitable work.

[27][28] In April 2013, the diocese fired Carla Hale, a teacher at Bishop Watterson High School in Columbus.

[31][32][33] Brennan initiated the elevation of Saint Mary of the Assumption in Lancaster to the rank of a minor basilica in August 2019.

[36] In February 2020, the diocese announced the closure of two diocesan retreat centers, St. Therese's in Columbus and Sts.

In 1939, the newspaper announced it would no longer associate with the diocese, but continued to publish until 1940, when it was replaced by The Columbus Register.

In 1951, the diocese established The Catholic Times, to replace The Columbus Register; it continues publication today.

[62] In 1993, Bishop Griffin removed Reverend Phillip Jacobs from his parish due to allegations that he had sexually abused a teenage boy.

[64] In August 2018, Bishop Campbell and the diocese were named in a $2 million lawsuit by Kevin Heidtman, a former student at St. Charles Preparatory School in Columbus.

The lawsuit alleged that Campbell and the diocese became aware of Bennett's molestation of Heidtman, but failed to take any action.

[72] The diocese hired an outside licensed counselor in July 2020, coinciding with the formation of a Safe Environment Task Force by Bishop Brennan.