Microplastics, particularly polystyrene (PS), are ubiquitous environmental contaminants and concerns about their potential detrimental effects on human health are increasing. Emerging evidence suggests that microplastics may disrupt the gut microbiota, a critical ecosystem involved in regulating host metabolism, immunity, and aging processes. However, the specific effects of PS on the gut microbiota composition and its potential role in modulating aging are yet to be fully elucidated. In this study, we aimed to investigate the effects of PS exposure on gut microbiota dysbiosis and its potential role in the acceleration of aging. Gut microbiota composition was assessed using 16S rDNA sequencing, while fecal metabolites were analyzed using gas chromatography-mass spectrometry. Exposure to PS resulted in a significant reduction in the abundance of beneficial microbiota, including . In contrast, there was an increase in the relative abundance of potentially harmful taxa, such as , and . Metabolomic analysis revealed elevated levels of several metabolites associated with stress responses and altered host metabolism, including alanine, serine, tryptophan, 5-aminovaleric acid, thymine, threonine, methionine, and benzoic acid. These findings demonstrate that PS exposure in aged mice exacerbated gut microbiome dysbiosis and altered key metabolic markers associated with aging, suggesting an increased vulnerability to age-related diseases as a consequence of microplastic exposure.