Objectives The primary aims of this study were the assessment of nutritional status based on Global Leadership Initiative on Malnutrition (GLIM) criteria 2019 and Subjective Global Assessment (SGA) as well as quality of life (QOL) with World Health Organization Quality of Life-BREF questionnaire (WHOQOL-BREF) of advanced cancer patients. The secondary aim was to investigate the impact of severity of malnutrition on QOL of these patients. Results This study included 33 advanced cancer patients from Nutritional Counselling Centre Copernicus in Gdansk and Department of Surgical Oncology, Medical University in Gdansk, Poland. The majority of patients suffered from head/neck (n=12, 33.33%) and espohageal cancer (n=11, 33.33%). According to the SGA method, most of the patients were malnourished (n=14, 42.42%) and severely malnourished (n=14, 42.42%). Based on the GLIM criteria, 69.7% of patients (n=23) were severely malnourished. Among all participants, the highest impairment of QOL in self-assessment of satisfaction of health, environmental, and psychological domain was observed. The severe malnutrition significantly impairs QOL in psychological (GLIM stage 2, p=0.0033; SGA C, p=0.0310) and somatic domain (GLIM stage 2, p=0.0423). This is the first study assessing the impact of severity of malnutrition based on new GLIM criteria on QOL of advanced cancer patients.