The human gut microbiome is a metabolically active and ecologically dynamic consortium that profoundly influences host physiology, in part by modulating epigenetic mechanisms such as DNA and RNA methylation. These modifications regulate gene expression and phenotypic plasticity and are shaped by a combination of environmental factors, such as diet, stress, xenobiotics, and bioactive microbial metabolites. Despite growing evidence linking microbial signals to host epigenetic reprogramming, the underlying molecular pathways remain incompletely understood. This review highlights recent mechanistic discoveries and conceptual advances in understanding microbiome-host epigenome interactions. We discuss evolutionarily conserved pathways through which gut microbiota regulate host methylation patterns, including one-carbon metabolism, polyamine biosynthesis, short-chain fatty acid signaling, and extracellular vesicle-mediated communication. We also examine how host factors such as aging, diet, immune activity, and sociocultural context reciprocally influence microbial composition and function. Beyond basic mechanisms, we outline translational frontiers-including biomarker discovery, live biotherapeutic interventions, fecal microbiota transplantation, and adaptive clinical trial designs-that may enable microbiome-informed approaches to disease prevention and treatment. Advances in high-throughput methylation mapping, artificial intelligence, and single-cell multi-omics are accelerating our ability to model these complex interactions at high resolution. Finally, we emphasize the importance of rigorous standardization and ethical data governance through frameworks such as the FAIR and CARE principles. Deepening our understanding of how the gut microbiome modulates host epigenetic programs offers novel opportunities for precision health strategies and equitable clinical translation.