Physical exercise has long been recognized for its numerous benefits to physical health, yet its profound effects on mental health are equally significant. This chapter delves into the intricate relationship between exercise, mental health, and epigenetics, highlighting how recent advances in epigenetics have started to uncover the molecular mechanisms through which exercise enhances mental well-being. This chapter reviews evidence demonstrating that regular physical activity can alleviate symptoms of depression and anxiety, enhance stress resilience, improve cognitive function, and promote better sleep quality. Moreover, it explores the epigenetic molecular mechanisms underlying these mental health benefits, such as histone modifications, DNA methylation, and microRNA regulation. These mechanisms play a crucial role in mediating the positive effects of exercise on mental health by influencing gene expression without altering the DNA sequence. By elucidating these epigenetic changes, the work aims to establish a robust theoretical foundation for future research and to suggest potential directions for developing more effective and personalized interventions for mental health disorders. Ultimately, this exploration of the interplay between exercise, mental health, and epigenetics underscores the importance of continued scientific inquiry in this area. It positions epigenetics as a critical field with significant implications for advancing both prevention and treatment strategies in mental healthcare, paving the way for innovative approaches to enhancing mental well-being through physical activity.