This paper considers the mosaic floor of the cathedral of Otranto from the viewpoint of the relationship between the decorative program and the tradition of medieval historiography. Analysis of the mosaic’s organization shows that it is modeled on the universal chronicles. From this perspective, the study of literary sources demonstrates how historiographical and biblical motifs serve to build a picture of cosmic history that accommodates Norman sovereigns. The mosaic’s decorative motifs also function in constructing an image of royalty based on the concepts of legitimation and universal vocation of power themes that belong to a very widespread repertoire throughout the Mediterranean basin. Closely linked to the circulation of luxury objects, this visual lexis becomes the prerogative of the courtly cultures that dominated the area, where it is used to promote the ruling classes’ images.