Glioblastoma (GBM) is a highly malignant, invasive, and poorly prognosed brain tumor. Despite active treatment, patient survival remains limited. Recent research has shown that gut microbiota plays a significant role in GBM, influencing the effectiveness of immune checkpoint inhibitors (ICIs). Gut microbiota can affect immune homeostasis, immune cell function, and tumor progression through metabolites, immune cell infiltration, and inflammatory responses. Some gut bacteria can reverse T cell suppression, enhance anti-tumor activity, and improve ICI efficacy. Additionally, gut microbiota can influence drug metabolism, affecting drug concentration and bioavailability. The gut-brain axis also plays a role in regulating immune responses and tumor progression. Fecal microbiota transplantation (FMT) is being explored to improve ICI therapy in GBM patients. However, challenges remain, including the complexity and individual variability of gut microbiota, unclear mechanisms of action, and limitations in intervention methods. Further research is needed to understand the relationship between gut microbiota and tumor immunity to develop more effective, personalized ICI strategies for GBM.Glioblastoma (GBM) is a highly malignant, invasive, and poorly prognosed brain tumor. Despite active treatment, patient survival remains limited. Recent research has shown that gut microbiota plays a significant role in GBM, influencing the effectiveness of immune checkpoint inhibitors (ICIs). Gut microbiota can affect immune homeostasis, immune cell function, and tumor progression through metabolites, immune cell infiltration, and inflammatory responses. Some gut bacteria can reverse T cell suppression, enhance anti-tumor activity, and improve ICI efficacy. Additionally, gut microbiota can influence drug metabolism, affecting drug concentration and bioavailability. The gut-brain axis also plays a role in regulating immune responses and tumor progression. Fecal microbiota transplantation (FMT) is being explored to improve ICI therapy in GBM patients. However, challenges remain, including the complexity and individual variability of gut microbiota, unclear mechanisms of action, and limitations in intervention methods. Further research is needed to understand the relationship between gut microbiota and tumor immunity to develop more effective, personalized ICI strategies for GBM.