This protocol outlines the standardized procedures for utilizing fecal microbiota transplantation (FMT) in tumor immunology studies. FMT, the process of transferring gut microbiota from a healthy donor to a recipient, has shown potential in modulating the immune response against tumors. This protocol details the selection criteria for donors and recipients, preparation and processing of fecal material, and the administration routes for transplantation. Additionally, it describes the pre- and posttransplantation monitoring of microbiota composition, immune parameters, and tumor progression. By following this protocol, researchers can systematically investigate the impact of microbiota on tumor growth and immune modulation, contributing to the development of microbiota-based therapeutic strategies in oncology.