The Herbert J. Thomas Memorial Hospital in South Charleston opened in December 1946. The hospital was named for a local football star killed during World War II when he threw himself on a grenade. Thomas, a U.S. Marine sergeant, was posthumously awarded the Medal of Honor for his heroism.

To remedy the Kanawha Valley's hospital bed shortage, the city of South Charleston had begun construction of the hospital in 1943. Financed with $650,000 in federal grants and loans, the building was completed in July 1945. However, the city ran out of money before the hospital could be equipped, and a group of citizens from South Charleston and surrounding communities undertook to raise the necessary funds. The Herbert J. Thomas Memorial Hospital Association, chartered in July 1946, raised $250,000 to provide money for equipment and staff. The association continues to operate the hospital, leasing from the city, which owns the property and buildings.

Originally, the hospital had 70 beds and 100 employees. Through the years, Thomas Memorial Hospital has been renovated and expanded, and in 2019 was about three times its original size, with 241 beds and more than 1,000 employees. Hospital services include a cancer center, obstetric services, behavioral health services, lung center, sleep diagnostic center, physical therapy center, and a full range of imaging services.

In 2001, the Thomas emergency center expanded from 7,000 square feet to 13,000 square feet. The new facility included 20 beds on the emergency side and 10 beds in CareCenter24, which handles less serious matters. The most recent expansion at Thomas Memorial is a new four-story office building providing additional space for doctors affiliated with the hospital.

In 2007, Thomas Memorial bought Saint Francis Hospital in Charleston and created an umbrella organization, Thomas Health System, to oversee both facilities. In 2010, Thomas Memorial opened the Clinical Pavilion, a six-floor, $70 million dollar addition that includes all private rooms, obstetrics unit, surgical center, gift shop and café. In 2016, Thomas announced plans to build a $17 million post-acute care facility on its South Charleston campus. In January 2020 Thomas Health Systems filed for Chapter 11 bankruptcy. As of June 2020, Thomas Health served approximately 275,000 patients annually and employed approximately 1,650 people.

In 2022, the boards of directors of Thomas Health, Thomas Memorial, and Saint Francis voted to become affiliates of WVU Medicine, which in 2023 announced plans to convert Saint Francis into West Virginia's first full-service and comprehensive orthopedic hospital.