Due to their antimicrobial properties, silver nanoparticles (NPs) are used in a wide range of consumer products that includes topical wound dressings, coatings for biomedical devices, and food-packaging to extend the shelf-life. Despite their beneficial antimicrobial effects, developmental exposure to such NPs may lead to gut dysbiosis and long-term health consequences in exposed offspring. Silver NPs can cross the placenta and blood-brain-barrier to translocate in the brain of offspring. The underlying hypothesis tested in the current study was that developmental exposure of male and female mice to silver NPs disrupts the microbiome-gut-brain axis. To examine for such effects, C57BL6 female mice were exposed orally to silver NPs at a dose of 3 mg/kg BW or vehicle control two weeks prior to breeding and throughout gestation. Male and female offspring were tested in various mazes that measure different behavioral domains, and the gut microbial profiles were surveyed from 30 through 120 days of age. Our study results suggest that developmental exposure results in increased likelihood of engaging in repetitive behaviors and reductions in resident microglial cells. Echo-MRI results indicate increased body fat in offspring exposed to NP exhibit. Coprobacillus spp., Mucispirillum spp., and Bifidobacterium spp. were reduced, while Prevotella spp., Bacillus spp., Planococcaceae, Staphylococcus spp., Enterococcus spp., and Ruminococcus spp. were increased in those developmentally exposed to NPs. These bacterial changes were linked to behavioral and metabolic alterations. In conclusion, developmental exposure of silver NPs results in long term gut dysbiosis, body fat increase and neurobehavioral alterations in offspring.