Introduction: Hospital malnutrition (HM) in children augments morbidity and mortality, thus early detection is a preventive measure that may improve a patient’s condition. This study identified the risk factors of HM among children hospitalised in Universitas Sebelas Maret (UNS) Hospital using the STRONGkids method. Methods: This observational analytical cross-sectional study was performed in children hospitalised at the paediatric ward of UNS Hospital between February and August 2021. The samples were taken by consecutive sampling technique. Subjects meeting the inclusion criteria were assessed for their underlying disease, nutritional status based on World Health Organization Anthro software, and STRONGkids score. Chi-square test and logistic regression analysis were used, with a p-value of <0.05 considered as statistical significance. Results: A total of 173 children were included in the study, 56% were males, mean age was 62.5 months, 45% had an underlying chronic disease, and 17.9% experienced moderate malnutrition. Based on the STRONGkids score, 39.3% children were at high risk of malnutrition and 60.7% were at moderate risk of malnutrition. Logistic regression analysis showed that high risk of HM was significantly associated with age (OR 2.58, 95% CI 1.38-4.84, p=0.003), chronic disease (OR 7.23, 95% CI 3.3-15.86, p=0.018), and moderate malnutrition (OR 13.5, 95% CI 3.96-45.98, p<0.001). Conclusion: Children hospitalised in UNS Hospital were at risk of malnutrition. Toddlerhood, chronic disease, and moderate malnutrition significantly increased the risk of HM. Thus, these children need optimal nutritional support to improve their clinical condition. STRONGkids is a convenient and easy method to identify malnutrition risk during hospitalisation.