This paper offers an analysis of the intricate role of color symbolism in shaping political legitimacy within the Fatimid Empire during the 10th and 11th centuries. Focusing on the significance of white as the official color of the Fatimid regime, it contrasts this choice with the contemporaneous associations of black with the Abbasids and red with the Umayyads. Drawing on a wide array of historical references, including court ceremonies, attire regulations for official khatībs, banners, and religious symbols such as the caliphs' parasol and the Ka'ba’s kiswat, the paper elucidates how color became a potent tool for shaping Fatimid identity and expressing their legitimacy. A central component of this exploration is the examination of the theological justifications for white provided in the fiqh texts of al-Qadi al-Nu'man, which highlight the Fatimid disdain for red associated with the Umayyads and the rejection of Abbasid black, underscoring the ideological rivalry between the two dynasties. Building on Khalil ʿAthamina’s research on the Abbasid black banners and Maribel Fierro’s work on the Umayyad use of red in Andalus, this paper analyzes how the Fatimids' choice of white served as a countersymbol which delineated themselves from their rivals. Furthermore, the paper delves into the contrasting messianic narratives of the Abbasids and Fatimids, revealing divergent interpretations of black banners. While the Abbasids claimed prophesies regarding the rise of such black banners, the Fatimids rejected this symbolism, associating black banners with false claimants, instead prophesying the rise of the true Mahdi from the Maghrib. This ideological divergence highlights the strategic deployment of color symbolism to assert legitimacy and ideological superiority. By contextualizing the discourse within the broader socio-political milieu of the Middle East during this period, this paper sheds light on the multifaceted ways in which color symbolism intersected with power dynamics, religious ideology, and identity construction. Through an analysis of primary sources, including fiqh treatises, court poetry, and historical narratives, it offers a nuanced understanding of how color emerged as a visual lexicon through which political and religious allegiances were articulated and contested.