American Public University System

The university was founded in 1991 by Major James P. Etter (USMC, retired) as American Military University. Operations began in January 1993 with the enrollment of 18 graduate students. Initially, the main goal of the university was to meet the unique educational needs of military personnel needing courses in specialized areas, such as counterterrorism and military intelligence, that were not included in typical university course offerings. In the early years, instruction was done through conventional correspondence.

In June 1995 AMU became nationally accredited by the Accrediting Commission of the Distance Education and Training Council (DETC). In January of the following year, the school introduced its first undergraduate programs. The first online courses and online classrooms started in 1998. In 1999, all undergraduate classes and programs went fully online, with graduate programs shifting to online in 2000.

In 2002 AMU expanded to become American Public University System and established American Public University, intended primarily for civilians interested in public service programs. In 2006 APUS was granted regional accreditation from the Higher Learning Commission. In 2012 American Public University System resigned its DETC accreditation. In 2016, the university was listed as tied for 58th place in U.S. News & World Report ranking of online bachelor's degree Programs.

In July 2016, long-time president Wallace E. Boston was succeeded as APUS president by former executive vice president and provost Karan Powell, while continuing his leadership role as CEO of APEI to provide strategic and leadership support to APUS and other APEI ventures. In September 2016, Vernon Smith was named senior vice president and provost, succeeding Powell. In September 2017, Boston was reappointed APUS president. In September 2019, Angela Selden was named CEO of APEI, succeeding Boston as head of the parent company.

APUS had a partnership with Walmart from 2010 to 2019. Walmart spent $50 million on the "Lifelong Learning Program, chiefly for tuition grants for Walmart workers to 'further develop a pipeline' for leaders".

From 2013 to 2017, APUS' enrollment declined from 127,000 to 84,000 students. In 2018, APUS paid the state of Massachusetts $270,000 after an investigation by the state's attorney general into allegations that it violated the state's for-profit and occupational school regulations, which are aimed at protecting students from the deceptive and unfair business practices by for-profit schools. In July 2020, Wade Dyke, former president of Kaplan University was named president of APUS; he was replaced by long-serving APUS board chair Dr. Katherine Zatz on November 4, 2021, who was the acting president until Nuno Fernandes took over on September 1, 2022.

In October 2020, parent company APEI began the process of acquiring Rasmussen College, later named Rasmussen University.

Under the 90–10 rule, schools are required to get funds that are not federal funds. In 2021, Congress closed the loophole in the 90–10 rule that previously excluded DOD Tuition Assistance funds and GI Bill funds. The Veterans Education Project reported that American Public University System would be the largest for-profit college chain negatively affected by the modified rule.