The interplay between the human gut microbiota and the peripheral immune system significantly affects the efficacy of immune checkpoint inhibitors (ICIs) in cancer therapy. Despite this profound connection, the practical implications of microbiota dysbiosis in cancer immunotherapy ICIs & and CAR-T remain intricate and poorly understood in practical terms. This paper offers a comprehensive review of current literature on the role of gut microbiota dysbiosis in tumor development, and emerging microbiota modulation interventions, with a focus on fecal microbiota transplantation (FMT). FMT is a cost-effective therapeutic avenue, particularly in addressing diseases rooted in antibiotic-resistant bacteria, such as Clostridium difficile. Here we provided insights into the applications of FMT and other gut microbiota therapies in the landscape of cancer treatment, emphasizing their influence on the tumor microenvironment and the efficacy of ICIs with suggestions for future research directions and their implications for clinical practice.