This study focuses on the Bhaiṣajyaguru faith, a core component of folk belief during the late Joseon dynasty, and examines its iconographic expression in the form of single-composition Bhaiṣajyaguru Paintings. The Bhaiṣajyaguru faith, centered on the Buddha’s vow to relieve the suffering of sentient beings, has been transmitted since the Three Kingdoms period and continued to thrive during the Joseon era. This faith was visually articulated through Bhaiṣajyaguru Paintings, which served as a form of religious expression. Previous research has predominantly focused on triadic Bhaiṣajyaguru Paintings, the iconography and roles of the Twelve Yakṣa Generals, and the origins of the Four Celestial Kings. However, there has been limited systematic research on the formal transformation and religious context of single-composition Bhaiṣajyaguru Paintings in the late Joseon period. This study fills this gap by classifying the single-composition Bhaiṣajyaguru Paintings into three types: Type I includes the Twelve Yakṣa Generals, Type II features the Four Celestial Kings, and Type III depicts Bhaiṣajyaguru in a triad format. Based on textual research and iconographic analysis, the study examines representative examples from Songgwangsa, Tongdosa, Jeondeungsa, Jijangsa, and Bunhwangsa temples. The findings reveal the visual representation of Bhaiṣajyaguru faith and its significance as a folk belief. Furthermore, the study uncovers how changes in painting formats were intertwined with shifts in religious devotion during the late Joseon period, offering significant insight into the evolution of religious art and its societal impact.