Objective: To investigate the prevalence and predictive factors of malnourishment in patients with gynecologic cancer during chemotherapy. Methods: A total of 101 patients treated with chemotherapy between April 2020 and February 2021 were interviewed using the patient-generated subjective global assessment (PG-SGA). Clinical and laboratory data were also collected. The total number of lymphocytes per cubic milliliter (total lymphocyte count, TLC) and serum albumin were calculated to provide an optimal cut-off point using receiver operating characteristic curves. Clinicopathological variables were compared using univariate and multivariate analyses to identify the independent predictive factors for malnourishment. Results: The prevalence of good, moderate, and severe nourishment was 73.3%, 18.8%, and 7.9%, respectively. The optimal cut-off points for TLC and albumin were 1,450 cells/μL and for albumin was 3.9 g/dL. Univariate analysis indicated that the number of chemotherapy cycles ≤3, albumin level ≤3.95 g/dL, body mass index ≤25 kg/m2, TLC <1,450 cells/μL, anemia, and no neutropenia were significantly associated with malnutrition. However, only a serum albumin level ≤3.95 g/dL was independently associated with malnourishment. Conclusion Patients with gynecologic cancer treated with chemotherapy were occasionally found to be malnourished, with the independent predictive predictor being a blood albumin level less than or equal to 3.95 g/dL.