Nutritional and metabolic status demonstrates dynamic interplay with immune function status and immunotherapy efficacy including treatment - related toxicity tolerance in cancer patients and shows significant correlation with immunotherapy prognosis. Macroscopically tumor-associated metabolic disorders encompassing host anti-tumor stress responses and cancer-derived metabolic abnormalities trigger protein - energy wasting imbalance accompanied by reduced dietary intake and activity restriction leading to progressive malnutrition or even cachexia which further diminishes immunotherapy response rates and treatment tolerance. Microscopically the nutrient - deprived hypoxic and acidotic tumor microenvironment disrupts immune cell metabolic reprogramming thereby suppressing their antitumor efficacy and establishing a vicious cycle of immune escape. Nutritional assessment constitutes a crucial component of baseline evaluation prior to cancer immunotherapy enabling clinicians to better identify beneficiaries from immunotherapy and formulate personalized treatment strategies. Consequently prognostic indicators integrating nutritional and immune parameters e. g. prognostic nutritional index geriatric nutritional risk index have emerged as potential biomarkers for predicting immunotherapy outcomes. This review synthesizes current understanding of cancer-associated metabolic characteristics their immunomodulatory impacts and advances in nutritional biomarkers for immunotherapy prognosis prediction aiming to provide clinical reference value.