This study investigates the contribution of moral megametaphors to the macrostructure of Oscar Wilde's seminal novel, "The Picture of Dorian Gray." The Conceptual Metaphor Theory (CMT) and Conceptual Blending Theory (CBT) were employed for systematic and well-grounded analysis. The study adopted a qualitative approach, using case study design and thematic analysis, to explore the role of moral megametaphors in developing the narrative structure, character progression, and literary themes. Results reveal that the moral megametaphors frequently used in the novel include the conceptual metaphors, i.e., MORALITY IS BEAUTY, MORALITY IS PURITY, and THE SOUL IS A LIVING ENTITY, and metaphorical blends, i.e., THE SOUL IS A PORTRAIT and MORALITY IS THE EXTERNAL APPEARANCE OF THE PORTRAIT. These megametaphors (1) enhance the textual coherence by connecting several micrometaphors; (2) develop the narrative structure with the portrait as a visual, dynamic manifestation of corruption; and (3) reinforce the writer's message on aesthetic beauty and moral decay. The study offers valuable insights for both research and practice by extending the application of CMT and CBT in literary analysis and providing practical guidance for teaching literature and translating metaphors. While acknowledging certain limitations, the study encourages future research to explore broader themes and adopt more objective approaches to further deepen the understanding of metaphor's role in literary macrostructure.