Natural light is one of the most important factors influencing spatial quality in Islamic and traditional architecture, serving not only as a source of illumination but also playing a decisive role in meaning-making, psychological perception, and the organization of spatial movement. Among various traditional building types, Ottoman bathhouses (hammams) are prominent architectural spaces in which lighting held special significance. However, the precise relationship between natural light and spatial quality in these baths-particularly from the perspective of environmental perception-has received limited scholarly attention. Therefore, the present study aims to analyze the impact of natural lighting on the spatial quality of Ottoman hammams, focusing on its role in enhancing spatial perception, psychological tranquility, and users’ ritual experience within these spaces. The research method is qualitative, based on a descriptive–analytical approach, integrating literature review, comparative analysis, and examination of architectural evidence in selected case studies of Ottoman hammams. The findings reveal that natural light in Ottoman bathhouses was employed not merely for illumination but functioned as a semantic and structural element in spatial organization. The distribution of light across walls and domes-especially through ceiling skylights-was executed in a controlled manner, creating inward-oriented, serene, and hierarchically defined spaces. In the hot room (sıcaklık/hararet), the focused beam of light on the central stone (göbek taşı) emphasized spatial centrality and guided users’ orientation. In the private chambers (halvets), soft lighting enhanced feelings of calm and security. The contrast in lighting across different spaces-such as the dressing room (soyunmalık/camekân), the intermediate warm room (ılıklık), and the hot room-not only improved spatial legibility but also created a ritual-like experience throughout the sequence of movement. Ultimately, the results indicate that natural light, interacting with architectural structure and cultural content, constitutes a fundamental factor in generating the desired spatial quality in Ottoman hammam architecture.