Radiant cooling systems have recently attracted great interest; they are now widely used in the world owing to their ability to save energy and provide better thermal comfort. Considering the expected increase in the consumption of energy in the future, the use of radiant cooling systems is expected to rise concurrently. However, radiant cooling systems are limited in their humidity control. Hence, the use of radiant cooling can be problematic in locations that experience hot and humid climates, such as Japan. The objective of this study is to understand the thermal comfort performance of radiant cooling systems in hot and humid climates with different operation methods. For this purpose, a subjective test was conducted during the summer and intermediate seasons. As a result, it was concluded that a better thermal comfort performance can be achieved using radiant cooling and natural ventilation simultaneously during the summer and intermediate seasons.