The recovery and reuse of Municipal Solid Waste (MSW) from old dumpsites is a promising approach to address environmental concerns while promoting resource recovery. This study investigates the composition and characterization of MSW retrieved from the Ariyamangalam dumpsite in Trichy, India, with a focus on its reuse potential in earthworks and agricultural applications. The MSW primarily comprises soil-like material (SLM), constituting 72–78% of the retrieved fraction, with significant amounts of organic matter, nutrients, and coarse particles. Physicochemical analyses revealed pH levels indicative of the humic phase, moderate amounts of nutrients, including nitrogen at 1.09%, phosphorus at 0.55%, and potassium at 0.82%, and high levels of organic carbon, supporting potential reuse in non-agricultural compost applications. Geotechnical assessments highlighted favorable properties for infrastructure uses, including optimum moisture content, shear strength, and grain size distribution comparable to local soils. However, the occurrence of high concentrations of heavy metals, including chromium, copper, and zinc, along with significant leachable contaminants, presents potential risks, making treatment essential before reuse. Pollution indices classified MSW contamination as moderate to strong for certain metals, restricting its use in sensitive land applications without precautionary measures. The study emphasizes the potential of MSW for controlled reuse in infrastructure development and non-edible vegetation, provided proper treatments, such as washing and blending, are implemented to reduce contamination risks. These findings underscore the importance of landfill mining as a sustainable waste management strategy aligned with circular economy principles.