The third wave of the COVID-19 outbreak, in December 2020, overwhelmed the Korean healthcare system. In particular, the medical demand of residents in long-term care facilities, homeless shelters, group homes, and detention facilities surged. In this study, we described the experience from development and operation of an alternate care facility (ACF) against the COVID-19 pandemic. In this study, we describe our implementation strategy, including the layout plan, adequate staffing, admission criteria, and patient flow. Using the context of the existing guidelines and literature in the planning and construction process, the differences from the preceding alternative treatment facilities to respond to COVID-19 were also described. Under the time pressure, the old buildings used as office spaces by the US armies were converted into a 107-bed hospital that met infection prevention and clinical care standards. Since these hospitals were dedicated to caring for the patients with COVID-19, multiple challenges were posed to the standards of infection prevention and control, and patient care and safety. The approaches described here provide a potential roadmap for decision makers, who are coping with medical surges as a result of the current and potential future pandemics by implementing an ACF.