Epigenetic mechanisms in entomology are gaining increasing importance in terms of their molecular foundations, biological functions, and applied aspects. Gene expression is dynamically regulated by DNA methylation, histone modifications, and RNA-mediated pathways in response to environmental conditions. In insects, these mechanisms underlie caste differentiation, polyphenism, developmental plasticity, social behavior, and epigenetic memory. Moreover, host–pathogen interactions at the epigenetic level modulate immune responses and symbiotic balance, enabling adaptation to diverse stressors. The main objective of this study is to highlight the role of epigenetic regulation in insect biology and to emphasize its potential contributions to both basic research and applied entomology. Epigenetic processes are closely linked to pesticide resistance, the use of insects as environmental indicators, population adaptation, and transgenerational inheritance. Looking ahead, CRISPR/dCas9-based epigenetic editing, species-specific epigenetic maps, and the combined analysis of genetic, RNA, and protein data are expected to play a crucial role in advancing both fundamental insights and practical strategies in insect science. Ultimately, epigenetics offers a transformative paradigm for understanding phenotypic diversity and adaptive capacity in insects, with significant implications for sustainable agriculture and ecological health.