In 1909, Athens citizens formed a new militia company. This company entered the Ohio National Guard as Company L, 7th Infantry. Co. L initially held drill in the Campbell Block, located on the corner of Court and State Streets. In 1912, the state's Armory Board approved Co. L's request for an armory. Construction began in 1914 and the Armory opened for use in 1915. By then Athens had formed another militia company, the Machine-Gun Company, 7th Infantry, which also held drill in the Athens Armory.
Co. L and the Machine-Gun Company were mobilized in 1917 when the United States entered the First World War. They became part of the 37th "Buckeye" Division and served on the Western Front. In Athens, local organizations used the Armory to support the war effort and the county's draftees were inducted into service at the building. After the war, a Battery of the 134th Field Artillery, Ohio National Guard, held drill in the armory, until they were mobilized for service in World War II. During the Cold War, a battery of air defense artillery used the Armory, before the Ohio Army National Guard consolidated its formations and sent the air defense artillery to McConnelsville.
The Athens Armory served as a public event space in addition to its military role. Local organizations used the drill space for fundraisers, dances, rummage sales, and other large indoor events. Over the years the building became iconic of uptown Athens, and its likeness was used as the logo for the Growing Up in Athens project.
The city purchased the Armory from the Ohio National Guard in 1997, paying the sum of $300,000. Although city leaders had grand plans for the historic building, the structure has done little more than serve as storage for city records since the time of its purchase. A 2003 study revealed that the building needed over a million dollars worth of structural repairs, asbestos removal, and general improvements to bring the building up to modern standards. Since the study, the City has worked to maintain the building and put a new roof on the structure.
In 2018, a marker that details the history of the armory was unveiled. The marker came about through the combined efforts of the City of Athens, the Athens Historic Preservation Commission, and the Southeast Ohio History Center.