Diarrhea remains one of the major public health problems among children under five years of age. In the service area of UPTD Puskesmas Rawat Inap Bumidaya, 304 under-five children were identified with diarrhea in 2025, resulting in a prevalence of 13.86%. This study aimed to analyze factors associated with diarrhea among children under five in the service area of Puskesmas Rawat Inap Bumidaya. This study employed a sample of 184 children under five selected using proportional random sampling. The variables examined included the child's age, nutritional status, immunization status, water quality, latrine ownership, and waste management. Data were analyzed with the Chi-square test and multiple logistic regression. The results showed that the child's age (p = 0.005), nutritional status (p = 0.001), immunization status (p = 0.002), water quality (p = 0.001), latrine ownership (p = 0.008), and waste management (p = 0.000) were significantly associated with the occurrence of diarrhea among children under five. Waste management was the strongest predictor. Both host-related and environmental factors are associated with diarrhea among children under five, with waste management being the most influential factor. Therefore, improving waste management and strengthening promotive and preventive efforts through community education on proper household waste management that meets health standards are necessary, emphasizing the importance of separating organic and inorganic waste, using covered waste bins, and disposing of waste in designated disposal sites to reduce the incidence of diarrhea.