The gut microbiome plays a crucial role in modulating immune responses to viral infections, influencing both the efficacy of antiviral defenses and overall health. This review explores the intricate relationship between the gut microbiota and the immune system, focusing on mechanisms of microbial modulation, the impact of gut dysbiosis on viral pathogenesis, and the influence of specific microbial taxa on immune outcomes during viral infections such as influenza and COVID-19. Additionally, we discuss microbial metabolites, particularly short-chain fatty acids, and their immunomodulatory effects, as well as current and emerging therapeutic strategies targeting the gut microbiome to enhance antiviral immunity. Future research directions are highlighted, emphasizing the need for standardized methodologies and personalized approaches to microbiome interventions. Understanding the gut-immune axis opens promising avenues for innovative therapies to improve resilience against viral infections.