Persian script, in its various forms of Islamic calligraphy, has profound and significant impacts on Iranian architecture. These influences can be categorized into aesthetic, spiritual, cultural, educational, and social dimensions. Aesthetically, Persian script, recognized as one of the most beautiful forms of Islamic art, adorns the architectural facades of mosques. The use of diverse calligraphic styles, such as Thuluth and Naskh, adds even more appeal to their designs. From a spiritual perspective, inscribing Quranic verses and Persian poetry on mosque facades fosters a deeper connection with God and reinforces the cultural identity of Iranians. One of the influential mosques on Iranian architecture is the Sheikh Lotfallah Mosque in Isfahan, where the characteristics of Persian script are clearly evident. The aim of this research is to examine the impact of Persian script on the semiotics of Iranian architecture, particularly in mosques. The research method is descriptive-analytical and has practical objectives. Data is collected through library and documentary methods, utilizing content analysis and deductive reasoning. The findings indicate that Persian script significantly influences Iranian architecture in aesthetic, spiritual, philosophical, cultural, and social dimensions. Consequently, based on educational, ethical, social, cultural, and artistic criteria, this impact is discernible in all architectural works in Iran, especially following the advent of Islam.