The Diocese of Steubenville (Latin: Dioecesis Steubenvicensis) is a Latin Church ecclesiastical territory, or diocese, of the Catholic Church covering thirteen counties in southeastern Ohio in the United States.

The Diocese of Steubenville is a suffragan diocese in the ecclesiastical province of the metropolitan Archdiocese of Cincinnati. The seat for the diocese is Holy Name Cathedral in Steubenville.

During the 17th century, present day Ohio was part of the French colony of New France. The Diocese of Quebec had jurisdiction over the region. In 1763, after the French-Indian War, Ohio Country became part of the British Province of Quebec. To prevent hostile interactions with Native Americans in the area, the British had forbidden settlement in Ohio by inhabitants of the 13 American colonies. After the American Revolution, the Ohio area became part of the new United States. In 1784, the Vatican established the Apostolic Prefecture of the United States so as to remove American Catholics from the jurisdiction of a British diocese.

The Vatican erected the Diocese of Baltimore in 1789 in place of the prefecture. In 1808, Pope Pius VII erected the Diocese of Bardstown in Kentucky, a vast diocese with jurisdiction over the new state of Ohio along with the other midwest states. Pope Pius VII in 1821, erected the Diocese of Cincinnati, taking the entire state of Ohio from the Diocese of Bardstown.

The first Catholic church in Steubenville, St. Peter's, was dedicated in 1835.

In 1868, Pope Pius IX erected the Diocese of Columbus, encompassing the portions of Ohio "...lying south of 40' and 41" and between the Ohio River on the East and the Scioto River on the West together with the Counties of Franklin, Delaware and Morrow."

Pope Pius XII erected the Diocese of Steubenville on October 21, 1944, from thirteen counties (Carroll, Jefferson, Harrison, Guernsey, Belmont, Noble, Monroe, Morgan, Washington, Athens, Meigs, Gallia, and Lawrence) previously part of the Diocese of Columbus. The pope appointed Reverend Anthony Mussio of Cincinnati as the first bishop of Steubenville.

In 1958, Mussio joined with the other Catholic bishops of Ohio in opposing a so-called right to work amendment to the Ohio Constitution that would have outlawed mandatory union membership in unionized workplaces. As bishop, Mussio established 73 parishes and 20 missions, the College of Steubenville in Steubenville, St. John Vianney Seminary, a Camaldolese hermitage, Samaritan House, Catholic Social Services, and St. John's Villa. He also founded the diocesan newspaper, The Steubenville Register. In accord with the Second Vatican Council's reforms, he established the Steubenville Ecumenical Institute to foster better relationships among Christians and Jews. After 33 years as bishop, Mussio retired in 1977.

Auxiliary Bishop Albert Ottenweller of the Diocese of Toledo was appointed bishop of Steubenville In 1977, by Pope Paul VI. In 1989, Ottenweller was arrested with other protestors outside a health clinic that provided abortion services for women in Youngstown, Ohio. Refusing to post bail, he spent six days in jail before his trial. Ottenweiller retired in 1992.

In 1992, Auxiliary Bishop Gilbert Sheldon of the Diocese of Cleveland was appointed bishop of the Diocese of Steubenville by Pope John Paul II. Sheldon retired in 2002, to be replaced by Reverend R. Daniel Conlon of the Archdiocese of Cincinnati.

In 2007, Conlon announced that the diocese planned to construct a new Triumph of the Cross Cathedral in Steubenville. Under the plan, the diocese would combine six parishes in the city (Holy Name Cathedral, Holy Rosary, St. Pius X, St. Anthony's, St. Stanislaus, and Servants of Christ the King) into a centrally-located cathedral parish to better accommodate the decreased number of parishioners and priests. The six parishes closed in 2008. However, after raising $8.5 million, Conlon shelved his plan in 2011, saying that it was far too risky to incur the construction debt.

Pope Benedict XVI named Conlon as bishop of the Diocese of Joliet in 2011 and replaced him in Steubenville with Reverend Jeffrey Monforton of the Archdiocese of Detroit.

In June 2013, Monforton announced that the diocese would retain the current cathedral and renovate it. His plan included upgraded technology to allow broadcast of masses and other events, installing security systems to allow 24-hour visitation and restoring the towers that had been were removed in a 1957 renovation. Monforton added that, whenever possible, the diocese would employ local residents and firms to perform work. The diocese would also work with Holy Trinity Greek Orthodox Church, the Public Library of Steubenville and Jefferson County to revitalize the neighborhood.

In 2017, the diocese embarked on a year of re-consecration to the Immaculate Heart of Mary, patroness of the diocese. The diocese formed an 18-person ad hoc task force to ascertain the present pastoral needs of the diocese. A survey was also shared with all the priests and parishioners.

In May 2018, the diocese discovered that its financial department had been misallocating funds from employee paychecks since 2004. Monforton started a forensic audit of the diocesan finances dating back to 2004. As a result of the audit, the diocese was forced to pay $3.5 million in employee taxes. This new financial liability forced the diocese to suspend plans to renovate Holy Name Cathedral. Following the enactment of austerity measures, the diocese balanced its financial standing. Vicar General Kurt Kemo resigned from his church positions; he was later convicted of felony theft, having stolen over $289,000 from the diocese.

In October 2022, the diocese announced that the Vatican was considering merging it with the Diocese of Columbus. A month later, after receiving significant negative feedback within the Diocese of Steubenville, Monforton announced that the proposal was on hold.

In September 2023, Pope Francis appointed Jeffrey M. Monforton as auxiliary bishop of Detroit, transferring him from the Diocese of Steubenville. Paul J. Bradley, bishop emeritus of Kalamazoo, was appointed apostolic administrator of Steubenville.

In October 2018, the Diocese of Steubenville published a list of 16 clergy and one seminarian who were either credibly accused of, or had admitted to, sexually abusing minors.

In November 2018, Reverend Henry Foxhoven of Glouster pleaded guilty to three counts of sexual battery of a 17-year-old girl. Foxhoven was sentenced to 12 years in prison with no early release. In June 2020, the Vatican defrocked Foxhaven. In January 2021, Monforton and the diocese were sued for $1 million by Foxhoven's victim. The plaintiff, listed as JW, said that Foxhoven impregnated her in 2017 when she was a young teenager attending his church. The suit also stated that an affidavit for a 2018 arrest warrant said that Foxhaven told Monforton that he had been "sexually involved with a juvenile member of his congregation and that she was now pregnant". The diocese settled the lawsuit with JW in July 2022.

Also in November 2018, a woman reported to the diocese that she had been raped multiple times between 2010 and 2013 at Franciscan University of Steubenville facility by Reverend David Morrier, a Franciscan priest. Morrier had been assigned by the university to counsel the college student, who was suffering from PTSD due to previous abuse. He told the plaintiff that she was possessed by demons and performed sexually explicit so-called exorcisms on her. He impregnated her in 2011. After hearing the allegations, the diocese immediately notified law enforcement; the Franciscan University had suspended Morrier from ministry in 2015 after receiving sexual misconduct allegations. In November 2021, Morrier was indicted on sexual battery and rape charges. He pleaded guilty in March 2022 to one count of sexual battery and was sentenced to five years of probation. The woman sued the university and the Franciscan Order, and reached a settlement with them in October 2022.

• Anthony John King Mussio (1945–1977)
• Albert Henry Ottenweller (1977–1992)
• Gilbert Ignatius Sheldon (1992–2002)
• Robert Daniel Conlon (2002–2011), appointed Bishop of Joliet in Illinois
• Jeffrey Marc Monforton (2012–2023)
  • Paul J. Bradley (Administrator, 2023-2024)
  • Edward M. Lohse (Administrator, 2024)

Roger Joseph Foys, appointed Bishop of Covington in 2002

• Catholic Central High School – Steubenville
• St. Joseph Central High School – Ironton

• Franciscan University of Steubenville – Steubenville

The Diocese of Steubenville contains the following counties:

• Athens
• Belmont
• Carroll
• Gallia
• Guernsey
• Harrison
• Jefferson
• Lawrence
• Meigs
• Morgan
• Monroe
• Noble
• Washington

• WILB "Living Bread Radio" 1060 AM in Canton

• Roman Catholic Diocese of Steubenville Official Site
• Triumph of the Cross Home Page

40°21′56″N 80°37′53″W / 40.36556°N 80.63139°W / 40.36556; -80.63139