Named after inventor of water chlorination Brigadier General Carl Rogers Darnall, MD., the core of the medical center is a state of the art 947,000-square-foot hospital.

The medical center is one of the largest in the Military Health System, comprising more than 105 buildings in addition to the main facility, spread over Fort Cavazos, three local communities, and a clinic at the Red River Army Depot in Bowie County, Texas, outside of Texarkana.

The medical center and its outlying facilities are staffed nearly entirely by uniformed servicemembers of the U.S. Army, however in 2019, the administrative control of the facility was shifted from United States Army Medical Command to the Defense Health Agency, an integrated joint Department of Defense combat support agency.

To meet the growing medical needs, the Army began a $49.7 million addition and reconstruction project in 1979 that was completed on December 13, 1984.

An expansion of the Darnall Army Community Hospital attempted to satisfy modern health care needs through upgrades and renovations.

The Army determined it required a brand-new facility with expanded services that would meet the Department of Defense's standards for care at the largest U.S. military base in the world.

In 2006, the Army announced that the new Fort Hood master plan designated a 40-acre (160,000 m2) site near the Clear Creek Post Exchange for a new medical facility to replace the existing structure.

It is the last project completed under the American Recovery and Reinvestment Act, and also the program's largest contribution to the Department of Defense.

The design also called for hard wearing interior fittings, with entirely stainless steel flashings and double- and triple-pane windows.

The medical center separates its services into what it calls 'portals of care', categorizing patient needs as primarily clinic-based or hospital-based.

Colonel Gibson said the McKinsey framework is “A watershed model that addresses the critical role of coordination, rather than structure, in organizational effectiveness, [incorporating] strategy, structure, systems, shared values, skills and staff.”[5] When the new hospital opened its doors in 2016 it replaced the old Darnall Army Medical Center that served the Fort Hood community since 1965.

Today, the new medical center serves more than 100,000 beneficiaries, which includes active duty soldiers, their families and retirees.