<p>This study evaluates the use of Construction and Demolition Waste (CDW) and marginal soil as alternative backfill materials for Mechanically Stabilized Earth (MSE) walls. CDW offers a sustainable solution to landfill waste but it can exhibit variable permeability depending on its gradation and fines content, uncontrolled fines may reduce drainage efficiency compared to well graded-granular soil. While marginal soil, characterized by high fines content and low permeability, is typically unsuitable as backfill. The research investigates different configurations: CDW alone, marginal soil alone, alternating layers of CDW and marginal soil, and conventional sand backfill. Scanning electron microscopy (SEM) was conducted on CDW samples with varying proportions of crushed materials to get the optimal proportion of CDW. The findings of the finite element method (FEM) based model revealed that CDW provides the highest factor of safety (FOS), with the combination of CDW and marginal soil in alternating layers further enhancing stability compared to marginal soil alone. The study highlights that using CDW and marginal soil can improve the stability of MSE walls while promoting environmental sustainability.</p>