<p>Reusing landfill-mined soil-like materials (SLM) following low-carbon remediation is critical for advancing the ecological transformation of old landfills. However, the durability of stabilized SLM in geotechnical applications remains inadequately characterized, particularly regarding its exposure to acid rain attack and undergoing dry–wet cycles coupled with acid attack. This study aims to systematically investigate the geo-environmental properties of stabilized SLM under simulated acid rain soaking and dry-simulated acid rain (D-A) cycling, focusing on the evolution of strength, mass loss, pH, heavy metal leaching, phase assemblage, micro-morphology, and pore structure. Moreover, the mechanisms underlying the performance degradation of stabilized SLM were revealed at multiple scales through a series of microscopic analyses. The results indicate that the synergistic application of stabilizing materials and oxidants significantly enhances the resistance of stabilized SLM specimens to both simulated acid rain soaking and D-A cycling. Particularly, after 10 D-A cycles, the average strength loss rate of the synergistically stabilized SLM specimens decreased by approximately 29%. The pH of the soaking solution displayed a rapid initial increase during simulated acid rain exposure, eventually stabilizing. In contrast, under D-A cycling, the pH exhibited a gradual decline, followed by a fluctuating pattern of increase and decrease after the fifth cycle. The simulated acid rain attack led to the dissolution of pozzolanic products, such as C-(A)-S–H gels, increasing pores and cracks, which subsequently impaired mechanical properties and facilitated heavy metal leaching. These findings hold significant implications for enhancing the service performance of stabilized SLM in geotechnical applications.</p>