Persistent accumulation of fly ash, a byproduct of coal combustion, poses significant environmental challenges due to its elevated levels of toxicity, heavy metal contamination, and ecological issues. Present review explores the ecological significance and functional potential of microfauna and mesofauna in mitigating environmental impacts, focusing on their ability to rehabilitate fly ash dump sites into biologically active and sustainable ecosystems. Microfaunal groups, including protozoa, nematodes, and other small invertebrates, play essential roles in promoting soil aggregation, pollutant biotransformation, and nutrient cycling while fostering synergistic interactions with plant communities to accelerate bioremediation processes and biodiversity recovery. The review also examines the constraints imposed by site-specific factors such as extreme pH, heavy metal toxicity, and organic matter deficiencies, offering targeted strategies to enhance remediation efficiency. It includes bioaugmentation with metal-tolerant strains, organic amendments to enrich soil fertility, and the integration of mycorrhizal fungi to optimize nutrient uptake and establishement of vegetation. The findings underscore the transformative potential of microfauna and mesofauna-based approaches for sustainable fly ash management, emphasizing the need for interdisciplinary research and technological innovation to address the ecological and environmental challenges associated with fly ash disposal. This work highlights the promise of advancing microfauna-driven ecological restoration strategies to rehabilitate degraded landscapes and support long-term environmental resilience.