In May 1978, DePaul University hosted a meeting with representatives from Bradley, Dayton, Detroit, Illinois State, Loyola–Chicago, Air Force, and Xavier who all agreed in principle that a new athletic conference was needed. Further progress was made through a series of early 1979 meetings in San Francisco, Chicago, and St. Louis that included participation by Butler, Creighton, Marquette, and Oral Roberts. On June 16, 1979, the Midwestern City Conference (nicknamed the MCC or Midwestern City 6) was formed by charter members Butler, Evansville, Loyola, Oklahoma City, Oral Roberts, and Xavier, with Detroit joining the following year.^[1] As of the 2026–27 academic year^[update], Detroit, now known as Detroit Mercy, is the only remaining member from the league's original members.

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In 1980, the league established its headquarters in Champaign, Illinois. The MCC gained an automatic bid to the NCAA Division I men's basketball tournament in 1981, followed by the announcement that Saint Louis University would be joining the following season. The University of Notre Dame joined the conference for all sports except basketball and football in 1982. The conference attained automatic qualification for the NCAA Division I Baseball Championship in 1984 and the conference moved its headquarters to Indianapolis. Three changes occurred in the summer of 1985: Oklahoma City dropped out of the NCAA altogether; the conference name was altered slightly to Midwestern Collegiate Conference; and the conference began sponsoring women's athletics. The latter triggered Notre Dame's temporary withdrawal from the league as its women's teams were contracted to the North Star Conference. ESPN began televising the MCC Championship game^{[clarification needed]} in 1986. In 1987, Oral Roberts left the conference while Dayton joined and Notre Dame rejoined. The conference earned its first at-large bid to the men's basketball tournament and automatic qualification to the NCAA Division I men's soccer tournament in 1989. In 1991, the conference received an automatic bid to the NCAA Division I women's basketball tournament and lost members Marquette and Saint Louis. Duquesne and La Salle joined the MCC in 1992, the same year the conference gained an automatic berth to the NCAA Division I women's volleyball tournament. Duquesne and Dayton left the conference in 1993.

on December 9, 1993, when Cleveland State, UIC, Northern Illinois, Green Bay, Milwaukee, and Wright State left the Mid-Continent Conference to join the Midwestern Collegiate Conference beginning with the 1994–95 academic year.^[1] At the time, this was the largest non-merger conference expansion in NCAA history, a record surpassed by the seven-member addition to the Pac-12 Conference in 2026. With Evansville's departure to the Missouri Valley Conference, there were 12 league members. Xavier, Notre Dame, and La Salle withdrew the following summer of 1995, followed by Northern Illinois in 1997. The conference changed its name to the Horizon League on June 4, 2001, in part due to the initials causing confusion between the MCC and the Mid-Continent Conference, who also used the initials. That year, Youngstown State University joined from the Mid-Continent Conference, and on May 17, 2006, Valparaiso University announced it would do the same in 2007.^[2] In April 2013, the split of the original Big East Conference caused a ripple effect that fell to the Horizon League; Loyola announced that it would leave the Horizon League effective July 1 to join the Missouri Valley Conference, which itself lost Creighton to the reconfigured Big East.^[3]

Butler also left the Horizon League. It spent a season in the Atlantic 10 Conference before joining the Big East.

In June 2013, the Horizon League announced that Oakland University, formerly of the Summit League, would immediately replace Loyola within a month.^[4]

The next change in the Horizon League's membership came in 2015 with the arrival of Northern Kentucky University from the Atlantic Sun Conference.^[5]

Two more membership changes were announced near the end of the 2016–17 school year. Valparaiso announced on May 25, 2017, that it would leave for the Missouri Valley Conference effective July 1. The Crusaders replaced Wichita State, which announced that it would leave for the American Athletic Conference.^[6] Three days before Valparaiso's departure, the Horizon League Board of Directors unanimously approved the membership of Indiana University-Purdue University Indianapolis (IUPUI) to replace Valparaiso, also effective July 1.^[7] IUPUI was dissolved in 2024 and replaced by separate institutions affiliated with the Indiana University and Purdue University systems. At that time, the athletic program transferred to the new Indiana University Indianapolis with an athletic brand name of IU Indy, maintaining IUPUI's Division I and Horizon League memberships.

The start of the 2020s set further membership changes into motion, with the arrivals of Purdue Fort Wayne and Robert Morris from the Summit League and the Northeast Conference, respectively, announced on August 5, 2019,^[8] and June 15, 2020.^[9] This brought the Horizon League up to 12 full-time members for the first time since the 1994–95 season. It was short-lived, however, as the UIC Flames were reported to be following many of their former conference colleagues to the Missouri Valley Conference effective July 1, 2022.^[10]

On July 6, 2022, the Horizon League and Ohio Valley Conference (OVC) jointly announced that they would merge their men's tennis leagues under the Horizon League banner, effective immediately. The five OVC members that sponsored the sport became Horizon associates. At the same time, the Horizon announced that Belmont, which had just left the OVC for the Missouri Valley Conference (which sponsors tennis only for women), would become a men's tennis associate,^[11] and Chicago State, which became a D-I independent after leaving the Western Athletic Conference days earlier, would become an associate in both men's and women's tennis.^[12] The Horizon later lost men's associate Lindenwood when they dropped nine NCAA sports, including men's tennis, after the 2023–24 season.^[13] Men's and women's associate Chicago State also announced it would join the Northeast Conference, which sponsors both men's and women's tennis; however, CSU announced that it would keep its tennis programs in the Horizon League for one extra year before moving them to the NEC for the 2025–26 season.^[14]

Prior to the 2023–24 academic year, the conference announced a brand refresh with the introduction of a new secondary logo. The logo is a gold stylized H that incorporates the arch of the conference's primary logo and a number one to symbolize unity.^[15] The logo was promoted to primary status ahead of the 2024–25 academic year.

On February 24, 2025, multiple media reports indicated that Northern Illinois was set to rejoin the Horizon League in 2026, coinciding with NIU football becoming an affiliate member of the Mountain West Conference. The move became official on February 27, after approval by NIU's governing board.^[16][17][18] That May, men's tennis affiliate Eastern Illinois announced it was dropping that sport effective immediately, citing issues stemming from the impending settlement of the House v. NCAA legal case.^[19]

On October 30, 2025, conference commissioner Julie Roe Lach, who had served in the position since 2021, was announced to be leaving the conference at the end of the fall 2025 semester to join Pacers Sports & Entertainment as executive vice president.^[20] On December 1, COO Christine Neuman took over as interim commissioner during the search for a permanent replacement.^[21]

As of the 2026–27 academic year^[update], nine of the 12 full Horizon League members are former members of the Mid-Con (now known as the Summit League), with the exceptions being Detroit Mercy, Northern Kentucky, and Robert Morris.

Notes

Nicknames and school names reflect those used in the last school year of conference membership.

Notes

Notes

 Full member (all sports)   Associate member (sport)  Other Conference  Other Conference 

Notes

• During the 1987–88 school year, Notre Dame competed in the Division I ranks of the National Collegiate Athletic Association (NCAA) as an Independent.
• During the 1985–86 school year, Oklahoma City competed in the National Association of Intercollegiate Athletics (NAIA) as an Independent.
• During the 1981–82 school year, UIC competed in the Division I ranks of the National Collegiate Athletic Association (NCAA) as an Independent.

Men's varsity sports not sponsored by the Horizon League which are played by Horizon schools:

In addition to the above sports, Northern Kentucky also sponsors men's triathlon, which has no NCAA recognition of any kind.^[25]

Women's varsity sports not sponsored by the Horizon League which are played by Horizon schools: