Neutrophils, key players in the innate immune system, become activated following ischemic stroke. However, the influence of gut microbiota on neutrophil activation and its impact on inflammatory brain injury is not yet fully understood. In this study, we demonstrate that microbiota colonization in germ-free mice activates neutrophils and worsens disease outcomes. To investigate the phenotypic and molecular alterations in neutrophils, as well as their activity in stroke mice with either depleted or intact microbiota, we conducted a comparative proteomic analysis using liquid chromatography-based mass spectrometry. Our findings revealed that microbiota depletion leads to a downregulation of inflammatory proteins in circulating neutrophils and a reduction in neutrophil extracellular traps (NETs). A similar pattern was observed in neutrophils infiltrating the brain, accompanied by a decrease in infarct size and alleviated behavioral deficits.