NutritionDay (nDay) is a project established by the Medical University of Vienna and the European Society for Clinical Nutrition and Metabolism (ESPEN) to audit the nutritional status of hospitalized patients and nursing home residents. This study aimed to evaluate nDay data describing the prevalence of hospital malnutrition, nutritional risk factors, and elements of the nutritional care process implemented in hospital wards in 25 European countries and to compare the data derived from Poland with the data collected in all the European countries participating in the study. In total, 10,863 patients (European reference group: 10,863 participants including Poland: 498 participants) were involved in the study. The prevalence of malnutrition was identified on the basis of the ESPEN diagnostic criteria established in 2015, while the prevalence of nutritional risk factors was assessed by analyzing the following parameters: body mass index (BMI), score of Malnutrition Screening Tool (MST), recent weight loss, insufficient food intake, decreased appetite, increased number of drugs intake, reduced mobility, and poor self-reported health status. Malnutrition prevalence was 12.9% in patients from the European reference group and 9.4% in patients from Polish hospital wards (p < 0.05). However, the prevalence of some nutritional risk factors, i.e., recent weight loss, history of decreased food intake, and low actual food intake, were approximately four times more prevalent than diagnosed malnutrition (referring to approximately 40–50% of all participants). In comparison to the European reference group, the significant differences observed in Polish hospital wards concerned mainly dietitian’s involvement in the process of treating malnutrition (16% vs. 57.2%; p < 0.001); supply of special diets (8% vs. 16.1%; p < 0.0001); provision of oral nutritional support (ONS) (3.8% vs. 12.2%; p < 0.0001); prescription of enteral/parenteral nutrition therapy to hospitalized patients (8.2% vs. 11.7%; p < 0.001); as well as recording patient weight performed at hospital admission (100% vs. 72.9%; p < 0.0001), weekly (20% vs. 41.4%; p < 0.05), and occasionally (0% vs. 9.2%). These results indicate that the prevalence of malnutrition and malnutrition risk factors in hospitalized patients in Poland was slightly lower than in the European reference group. However, some elements of the nutritional care process in Polish hospitals were found insufficient and demand more attention.