Objectives The aim of this study was to assess the association between malnutrition status with the (Global Leadership Initiative on Malnutrition) GLIM criteria and 1-year mortality in hospitalized patients with hematologic malignancy. Methods This study included 120 hospitalized patients with hematologic malignancy. Patients who were at risk of malnutrition with NRS2002 were reevaluated with the GLIM criteria for defined malnutrition. Also, the mid-upper arm circumference (MUAC), calf circumference (CC), and handgrip (HG) were measured, and albumin, C reactive protein (CRP), and total protein were recorded to assess malnutrition-related factors. Results A total of 120 patients are with lymphoma, leukemia, and myeloma having a rate of 34.2%, 34.2%, and 31.6%, respectively, and risk of malnutrition with NRS2002 was established in 82% of patients. Malnutrition with GLIM criteria was seen in 25.8% of patients. The 1-year mortality rate was 41.7% (n = 50). Malnutrition was associated with higher mortality risk independently with age and duration of diagnosis (HR 3.55 (1.99-6.34), p = 0.001). Low HG (HR 0.51 (0.26-0.99), p = 0.03), low albumin (HR 0.39 (0.2-0.6), p = 0.001), and high CRP (HR 2.39 (1.36-4.20), p = 0.002) were significantly associated with increased mortality risk. In contrast, BMI, MUAC, FFMI, and CC were not associated with higher mortality. Conclusion Malnutrition is high with the GLIM criteria. Hospitalized patients with hematologic malignancy with malnutrition have a higher 1-year mortality risk.