Diarrheal illness remains one of the major causes of child morbidity and mortality in the world. It kills an estimated 2.5 million people each year, with about 60-70% of them being children under five years of age. The study was aimed to find out risk factors associated with prevalence of diarrhea among under 5 years' children in low socioeconomic area of urban Bangladesh. A cross-sectional study was conducted to assess the incidence and risk factors associated with diarrheal illness. A semi-structured questionnaire was used in this study to collect the data on incidence and risk factors associated with prevalence diarrheal illness. Data was analysed using SPSS 19 version. The majority of diarrheal diseases incidence were found among the children that their mothers/caretaker had below secondary level of education (63.2%). Most of the incidence were found among younger age group (≤3 years), almost all diarrheal incidence occurred among the children that did not completed their vaccination as scheduled, It has been seen that the diarrheal incidence also occurred among the children that were not exclusively breastfed. The prevalence of diarrheal illness was found to be 38 percent. The findings of this study revealed, the household storage of food, sources of drinking water, type of latrine used in the household, lack of maternal education, exclusive breastfeeding practices and vaccination schedule as risk factors of diarrhea among under 5 years old children.