Sodium benzoate (SB) is a widely used preservative in various food and beverage products such as sodas, condiments, fruit juices, and more. While the FDA approved rate of consumption of SB is at 0.1% of food weight, many food products have been found to exceed this level. There is strong evidence in the literature establishing the dietary influence on the gut microbiome and the gut-brain axis mediating metabolic, immune, and neurological functions, however not much is known about the chronic effects SB has on these functions. This study aims to investigate the potential implications of prolonged exposure to SB, particularly focusing on its impact on the gut microbiome and associated behavioral changes in mice. Our previous studies showed morphological changes in the gut wall, decreased mucus production, and inflammatory changes in response to long-term SB consumption in mice. In this study, female C57BL/6 mice after weaning were maintained on a standard rodent chow with or without 1% SB diet for nine months. Behavioral data were collected using the BORIS software for home cage test, open-field test, novel object test, as well as forced swim test for assessing overall activity, social interaction, and short-term memory. Gut microbiome from fecal and cecal samples were analyzed by 16S Illumina sequencing. The differences in microbial population between treatment groups were determined by QIIME2 metabarcoding bioinformatics analysis. Unique to the SB-treated mice were higher amounts of Firmicutes and Proteobacteria while the control group had higher amounts of Bacteroidetes. There was no difference in behavior between treatment groups for the small data set we analyzed thus far. Our data suggests that long-term SB consumption could alter the gut microbiome and hence potentially impact gut health and communication through the gut-brain axis.