The incidence of cancer has increased significantly over the past decades, posing significant challenges to cancer treatment. Immune checkpoint inhibitors (ICIs) have shown favorable remission in a wide range of cancer types, but their efficacy varies among patients. Emerging evidence suggests that gut microbiota can modulate anti-tumour immune responses and predict clinical outcomes. Fecal microbiota transplantation (FMT) is a promising approach to enhance the efficacy of ICIs by remodeling gut microbiota, regulating microbial metabolites, and altering the tumour microenvironment. However, the long-term safety of FMT remains a concern, necessitating rigorous screening. This review examines the current experimental and clinical evidence supporting the efficacy of FMT in boosting anti-tumour immune responses and reducing tumour-related complications. It also discusses the challenges and proposes feasible solutions for future clinical applications. The review highlights the complex relationship between gut microbiota and anti-tumour immunotherapy, emphasizing the potential of FMT as a synergistic therapy to enhance the effectiveness of ICIs.The incidence of cancer has increased significantly over the past decades, posing significant challenges to cancer treatment. Immune checkpoint inhibitors (ICIs) have shown favorable remission in a wide range of cancer types, but their efficacy varies among patients. Emerging evidence suggests that gut microbiota can modulate anti-tumour immune responses and predict clinical outcomes. Fecal microbiota transplantation (FMT) is a promising approach to enhance the efficacy of ICIs by remodeling gut microbiota, regulating microbial metabolites, and altering the tumour microenvironment. However, the long-term safety of FMT remains a concern, necessitating rigorous screening. This review examines the current experimental and clinical evidence supporting the efficacy of FMT in boosting anti-tumour immune responses and reducing tumour-related complications. It also discusses the challenges and proposes feasible solutions for future clinical applications. The review highlights the complex relationship between gut microbiota and anti-tumour immunotherapy, emphasizing the potential of FMT as a synergistic therapy to enhance the effectiveness of ICIs.