Background Few studies have investigated nutrition support pharmacy practices and interventions in bone marrow transplant units. This study aimed to analyze the interventions of clinical nutrition support pharmacists in hospitalized cancer patients undergoing bone marrow transplant at a comprehensive cancer center. Methods A retrospective analysis of 10925 electronically reported clinical pharmacist interventions of hospitalized cancer patients admitted to bone marrow transplant units from January 2020 to December 2022 was conducted. All patients’ records with nutrition support pharmacists’ interventions were included. Results The number of interventions was 1418. The acceptance rate of clinical nutrition support pharmacists’ interventions by physicians was 92%. The initiation of mineral/vitamin use was found to be the most frequent intervention of nutrition support pharmacists, followed by requesting laboratory tests. Conclusion Nutrition support pharmacists have a role in managing hospitalized cancer patients admitted to bone marrow transplant units. The prevailing intervention was the initiation of mineral/vitamin use. Further studies are needed to explore the barriers to implementing nutrition support pharmacy services and to optimize these services in different patient populations.