Selecting optimal landfill sites requires balancing environmental, socio-cultural, and economic considerations while supporting global sustainability objectives. This study develops an integrated framework for selecting suitable municipal solid waste landfill sites in the Manouba region of Tunisia by combining geographic information systems with multi-criteria decision-making methods. The approach applies the analytic hierarchy process for weighting sixteen environmental, socio-cultural, and economic factors, followed by a weighted linear combination. Sensitivity analysis was performed to assess the robustness of the weights, quantitative validation using remote sensing indices was conducted to verify the final site selection, and an outranking approach based on the ELECTRE III method was applied to rank and compare the highly suitable sites. The results revealed that more than 91 percent of the study area is unsuitable for landfill implementation due to strict environmental constraints, while only 1.34 percent is classified as highly suitable. These findings highlight the critical trade-offs between land availability and environmental protection in semi-arid regions. The limited availability of suitable land underscores the necessity of rigorous spatial planning to meet the Sustainable Development Goals, particularly those related to health, clean water, infrastructure, sustainable cities, responsible consumption, climate action, and life on land. By integrating local waste management planning with global sustainability objectives, this research provides a robust and replicable decision-support tool for policymakers to ensure informed and sustainable infrastructure development.