The Diocese of Jefferson City (Latin: Dioecesis Civitatis Jeffersoniensis) is a Latin Church ecclesiastical territory, or diocese, of the Catholic Church in the state of Missouri in the United States. It is a suffragan diocese in the ecclesiastical province of the metropolitan Archdiocese of St. Louis.

The mother church of the Diocese of Jefferson City is the Cathedral of Saint Joseph in Jefferson City.

As of 2023, the Diocese of Jefferson City had 93 parishes and nine missions. The diocese had 77 active diocesan priests, 18 priests from other dioceses, 27 nuns and 101 permanent deacons. The Catholic population was over 76,200.

The diocese consists of 38 counties in mainly rural northeastern and central Missouri, and includes the urban areas of Columbia and Jefferson City.

The first Catholic presence in present-day Missouri was that of the Jesuit missionary Reverend Jacques Marquette in 1673, who stopped in Perry County while voyaging down the Mississippi River. In present-day Hannibal, the first Catholic masses were celebrated by the Belgian missionary, Reverend Louis Hennepin, in 1680. During this period, the Catholics in the region were under the jurisdiction of the Diocese of San Cristobal de la Habana, based in Havana, Cuba.

French-Canadian settlers established St. Genevieve, the first parish in the archdiocese, in 1759 in Ste. Genevieve.With the end of the French and Indian War in 1763, Spain took control of the French territories west of the Mississippi River. In 1793, after the American Revolution, Pope Pius VI erected the Diocese of Louisiana and the Two Floridas, based in New Orleans. It encompassed all the Spanish territories on the continent, including the Missouri area. Due to politics in Europe, the new diocese did not receive a bishop until 1815.

In 1803, with the signing of the Louisiana Purchase, the United States took control from France of a vast area of the continent, including Missouri. Pope Pius VII in 1815 named Reverend Louis Dubourg from the Diocese of Baltimore as the first bishop of Louisiana and the Two Floridas.Due to concerns about his personal safety in New Orleans, DuBourg chose the City of St. Louis as his episcopal see.

On July 18, 1826, Pope Leo XII divided up the Diocese of Louisiana and the Two Floridas. One of the new dioceses was the Diocese of St. Louis, which included Missouri along with vast areas of the American Midwest and Great Plains Because of its size, the diocese was often referred to as the Rome of the West.The Jefferson City region would remain part of this diocese and others for the next 130 years.

The first German language parish west of the Mississippi River, St. Joseph, was founded in Westphalia, Missouri, in 1835. In Jefferson City, St. Peter's, the first Catholic church in that city, was dedicated in 1846. St. Patrick's was founded in 1862 in Rolla, Missouri, to minister to the Irish Catholic railroad workers there.

On July 2, 1956, Pope Pius XII established the Diocese of Jefferson City. Its territory was taken from the Archdiocese of St. Louis, the Diocese of Kansas City and the Diocese of Saint Joseph. The pope named Auxiliary Bishop Joseph M. Marling of Kansas City as the first bishop of the new diocese.

During his tenure, Marling oversaw the construction of a new cathedral, 25 churches, 29 schools, 30 rectories, 16 convents, and a Carmelite monastery. He also established the diocesan newspaper and missions in Peru. Marling retired in 1969.

Pope Paul VI appointed Reverend Michael McAuliffe of Kansas City as the second bishop of Jefferson City in 1969. In 1980, McAuliffe appeared before the Missouri General Assembly to support the passage of the Equal Rights Amendment to the US Constitution.

In 1982, Holy Family Parish in New Haven, Missouri, won a court battle with McAuliffe over the relocation of an ornate marble altar within the church sanctuary. McAuliffe stated that the guidelines of the Second Vatican Council, created during the 1960's, forced him to relocate the altar. The judge ordered McAuliffe and Holy Family to negotiate a solution. McAuliffe retired in 1997.

To replace McAuliffe, Pope John Paul II in 1997 named Monsignor John R. Gaydos of St. Louis as the next bishop of Jefferson City. Gaydos retired early in 2017 due to poor health.

The current bishop of Jefferson City, as of 2023, is Shawn McKnight from the Diocese of Wichita.

In November 2024, the diocese garnered controversy when Bishop McKnight issuing and swiftly rescinding a diocesan decree that banned several popular hymns, including “All Are Welcome” by Marty Haugen, from parishes in its boundaries. The initial decree, “Suggested Mass Settings and Prohibited Hymns.” After receiving passionate responses from the Catholic community, the diocese replaced the decree with a new directive emphasizing synodal consultation on liturgical music.

In 2001, Bishop Gaydos and the diocese were sued by a former student at St. Thomas Aquinas Preparatory Seminary in Hannibal. The plaintiff claimed that Bishop Anthony J. O'Connell of the Diocese of Palm Beach, then rector at the seminary, had sexually exploited him.

In 2002, a new report revealed that the Diocese of Jefferson City paid a secret settlement of $125,000 in 1996 to Christopher Dixon. A former seminarian, Dixon claimed to have been sexually abused by O'Connell in 1969 at the seminary. In 2002, O'Connell admitted abusing two boys at the seminary and resigned as bishop of Palm Beach. In May 2002, facing declining enrollment at Thomas Aquinas Seminary and pending more sexual abuse lawsuits, Gaydos closed it.

In 2003, Bishop McAuliffe and the diocese were sued by a North Carolina man who claimed to have been sexually molested by two diocesan priests when he was a child. That same year, Gaydos and the diocese were named in a sexual abuse lawsuit by a Missouri man. The plaintiff alleged that Reverend Gary Pool and Reverend Kevin Clohessy, two priests in the diocese, had sexually abused him for most of his childhood.

In 2015, the diocese settled for $40,000 a long-standing sexual abuse claim by David Clohessy, the brother of Keven Clohessy, against John Whiteley, a diocese priest. Clohessy had sued the diocese in 1991, claiming that Whitely, then a pastor at St. Pius X Parish in Moberly, had sexually abused him. Clohessy's case was dismissed in 1993 due to the Missouri statute of limitations. However, Clohessy renewed his claim in 2015 and the diocese decided that it was credible.

Bishop McKnight announced in 2020 that two diocesan priests, Reverend Robert Duesdieker and Reverend Mel Lahr, had been laicized by the Vatican due to credible accusations of sexual abuse of children. In January 2022, the diocese released a list of clergy accused of violating the Charter for The Protection of Children and Young People issued by the US Conference of Catholic Bishops.

In November 2023, the diocese barred Reverend Ignazio Medina from celebrating mass or hearing confessions. An adult had accused Medina of sexual soliciting them during confession in 2022. At that time, McKnight made this statement:

“I want to be clear that sexual solicitation during confession is a sacrilege, a crime in our Church, and a grave form of abuse; it cannot be tolerated.”

In July 2024, Medina pleaded guilty in court to stealing over $300,000 from St. Stanislaus Parish in Wardsville from 2013 to 2021.

1. Joseph M. Marling, C.PP.S. (1956-1969)
2. Michael Francis McAuliffe (1969-1997)
3. John R. Gaydos (1997-2017)
4. Shawn McKnight (2018–present)

Anthony Joseph O'Connell, appointed Bishop of Knoxville in 1988, later Bishop of Palm Beach, resigned due to sexual abuse admission.

The Diocese of Jefferson, as of 2023, had three high schools and 37 elementary schools, with a total student enrollment of approximately 6, 700. The high schools are:

• Helias Catholic High School – Jefferson City
• Sacred Heart High School – Sedalia
• Father Tolton Regional Catholic High School – Columbia

"The Catholic Missourian" is the official newspaper of the diocese.

The Alphonse J. Schwartze Memorial Catholic Center serves as the chancery offices for the Diocese of Jefferson City. Located adjacent to the Cathedral of Saint Joseph, it is the pastoral center and a headquarters for the diocese. The center is named for Alphonse J. Schwartze, a parishioner of St. Joseph's Church in Westphalia. Groundbreaking for the center took place in 2004.

The center building is 26,795 square feet (2,489.3 m) and contains 47 rooms, including the chapel and meeting rooms. The walls display gifts from the diocesan clergy and laity. Most of the original paintings were created by Louis Wellington McCorkle, a member of the American Artists Professional League. The Peruvian artwork was donated by the estate of Francis G. Gillgannon.

The Saint Alphonsus Chapel is dedicated to the Italian Bishop Alphonsus Maria de Liguori. It is dominated by an imported 4½ foot wooden image of Christ modeled after the Gero Crucifix of the Cathedral of St. Peter and the Virgin Mary in Cologne, Germany. The diocese selected this crucifix to link the occupation of the center with the 2005 World Youth Day in Cologne. The chapel seats 50 people.

• Rice, C. David (1999). "DuBourg, Louis William (1766–1833)". In Christensen, Lawrence O.; Foley, William E.; Kremer, Gary R.; Winn, Kenneth H. (eds.). Dictionary of Missouri Biography. Columbia, MO: University of Missouri Press. pp. 258–259. ISBN 0-8262-1222-0. Archived from the original on 23 December 2020. Retrieved 23 December 2020 – via Google Books.

• Official Site