BACKGROUND: Rikkunshito is a traditional Japanese herbal medicine known to alleviate chemotherapy-induced gastrointestinal symptoms. However, the clinical impact of rikkunshito on patients undergoing neoadjuvant or conversion chemotherapy followed by curative surgery for esophageal cancer remains unclear. METHODS: We analyzed 57 patients with esophageal cancer who underwent curative surgery with preoperative chemotherapy between April 2021 and December 2024. Patients who did and did not receive rikkunshito during chemotherapy were assigned to the rikkunshito and control groups, respectively. Nutritional status was evaluated using albumin levels, lymphocyte counts, prognostic nutritional index, geriatric nutritional risk index, body weight, and body mass index (BMI), and skeletal muscle area (SMA) at L3 before and after chemotherapy. Propensity score matching (PSM) based on baseline characteristics, including age, sex, initial BMI, clinical stage, chemotherapy regimen, and initial PNI and SMA was performed. RESULTS: Overall, the rikkunshito group showed significantly lower rates of body weight (p = 0.016) and BMI loss (p = 0.011) than controls. Although SMA reduction did not reach statistical significance, a trend toward preservation was observed (p = 0.093). After PSM (n = 16 per group), the rikkunshito group showed a significantly lower reduction in body weight (p = 0.031), BMI (p = 0.016), and SMA (p < 0.001). CONCLUSIONS: Rikkunshito administration during preoperative chemotherapy for esophageal cancer was associated with better preservation of body composition, including skeletal muscle mass. This suggests the potential role of rikkunshito as a supportive therapy to mitigate sarcopenia and nutritional decline during intensive treatment of esophageal cancer.