With the accelerating population aging process, increasing attention has been paid to the nutritional risks among elderly patients in the intensive care unit (ICU). Elderly patients are often complicated by decreased physiological reserve, reduced muscle mass, multiple comorbidities, and critical illness-related hypercatabolism. Therefore, nutritional assessment and supportive therapy are featured by substantial complexity and individual heterogeneity. Focusing on the association between malnutrition and clinical outcomes in elderly ICU patients, this article reviews commonly-used nutritional risk screening and assessment tools, compares the indications and initiation timing of oral nutritional supplements, enteral nutrition and parenteral nutrition, and summarizes the principles for supplying energy, protein, fat, vitamins, trace elements and electrolytes as well as key points for therapeutic monitoring. It aims to provide references for individualized and dynamic nutritional management of elderly critically ill patients.