This article examines the interrelationship between justice (dād) and joy (shādī) in Ferdowsi’s Shāhnāmeh, approached through the central Zoroastrian principle of wisdom (kherad). The study explores how these concepts emerge from the dual framework of “being” and “non-being,” or “light” and “darkness,” which reflects the moral tension between good and evil in human existence. In Ferdowsi’s vision, justice is the source of joy; each gives rise to the other and together they shape a harmonious and enlightened human order. Wisdom enables human beings to reach truth, which manifests the divine natural order attributed to Ahura Mazda. Justice, in turn, sustains social, natural, and psychological balance. Rooted in ancient Iranian ethical thought, this process transforms disorder into the moral and political harmony represented by Shahrivar (divine dominion). Through the union of wisdom and justice, Ferdowsi presents an ethical model grounded in empathy, responsibility, and collective well-being. Ultimately, the Shāhnāmeh portrays justice not only as a rational principle but also as a foundation for individual and communal joy. The enduring bond between wisdom and justice becomes the basis for a prosperous and harmonious society.