A semiotic analysis and examination of the symbolic motifs of the ideal king in Achaemenid reliefs can reveal new dimensions in the representation of royal power and the legitimacy of the monarch. This approach enables a more precise understanding of the visual and ideological mechanisms of the Achaemenid period, expanding our comprehension of why and how the concept of the ideal king emerged in ancient Iran. The aim of this study is to analyze the deployment of semiotic systems in constructing royal discourse and shaping the king’s identity. The research is based on a library-based methodology grounded in archaeological evidence, with analysis focused on visual elements and the semiotic structures of the king’s figure. Key motifs—including the four-winged man in Pasargadae, hybrid creatures, winged symbols, fire, bow, and lunar symbols—are examined. Additionally, the position of the king’s body as the center of authority is analyzed in banquet scenes, royal thrones, and battles with demonic beings. The findings indicate that these reliefs were not merely reflections of royal discourse but served as instruments for reproducing and consolidating the monarch’s authority. The interplay between religion, power, and the king’s body in the visual and textual sources of the period underscores the critical role of semiotic elements in legitimizing the throne. The results demonstrate that Achaemenid art, through semiotic mechanisms, established the ideal king as the axis of political and religious authority, simultaneously rearticulating the concepts of royal charisma within the visual framework of the era.