Formed in 1902, it is the third oldest athletic conference in the United States.

Former commissioners include Mike Cleary, who was the first General Manager of a professional basketball team to hire an African American head coach, and would later run the National Association of Collegiate Directors of Athletics (NACDA).

By 1934, the conference reached an all-time high of twenty-four members,[1] seeing many schools come and go throughout the upcoming decades.

By 2000, the conference solidified to its current form with the addition of its final school, Wilmington, to ten members.

On January 18, 2024, John Carroll University announces departure from the OAC to the North Coast Athletic Conference (NCAC), beginning in the 2025–26 academic year.