<p>The rapid growth of urban infrastructure has significantly increased construction and demolition waste generation, necessitating a systematic approach to landfill site selection. Existing studies often lack a comprehensive integration of social, environmental, and economic criteria and fail to account for regional variations and expert-driven prioritization. This study addresses these gaps by developing a geographic information system-based framework that integrates a magnitude-based fuzzy analytic hierarchy process to assess landfill suitability in Tanta City, Egypt. The fuzzy AHP method was applied to quantify the relative importance of thirteen criteria—derived from expert surveys, literature reviews, and field observations—by incorporating uncertainty and expert judgment in pairwise comparisons. The weighted criteria were then spatially analyzed to generate a suitability map. The results categorize landfill sites into five suitability classes, revealing that only 3% of the area is highly suitable, while 67.36% is unsuitable or of low suitability. Analysis of existing landfills indicates their placement was primarily influenced by immediate land availability or administrative convenience rather than a structured evaluation process. To enhance future landfill development, the study integrates land use analysis to identify optimal locations. The findings demonstrate strong alignment with sustainable development goals (SDGs), contributing 80% to sustainable cities and communities (SDG 11), 75% to industry, innovation, and infrastructure (SDG 9), and 73% to responsible consumption and production (SDG 12). This research provides a replicable methodology that supports policymakers in making informed, sustainable landfill siting decisions and fostering environmentally responsible waste management.</p>