Background: Undernutrition is an acute or chronic form that is a major public health concern in resource-limited settings. In addition to this, its dual relation to HIV infection results in physical, mental, social, economic, and life crises. It also affects children at an early age and it has adverse consequences in later life with poor survival outcomes. However, survival status and risk factors contributing to poor survival outcomes among undernourished children who are on antiretroviral therapy are not well investigated. Objective: To assess survival status of undernutrition and its predictors among children who are on ART in public health facilities, Bahir Dar town, North West Ethiopia, 2021. Methods: An institution-based retrospective cohort study design was conducted among 414 study participants. Computer-generated simple random sampling method was applied to include study participants. Data were extracted through chart review using structured checklists. All collected data were entered into epi data version 4.6 and was checked for their completeness, consistency and lastly exported to STATA version 14.0 for further analysis. Each independent predictor variable with a p-value < 0.2 in the bivariate analysis was included in the multivariable Cox proportional hazard regression model. In multivariable cox regression, variables having a p-value < 0.05 were considered as statistically significant. Results: In this study, about 23(5.56%) of participants were died (95% CI: 3.7- 8.2) which gives overall incidence rate of 11.6 deaths per 1000 child years observation (95%CI: 7.7- 17.5) with total follow up of 23760 months. In multivariable cox regression; baseline weight for age <-3 Z score (AHR= 4.9, 95% CI: 1.30-18.98), baseline height for age < -3 Z score (AHR=4.34, 95%CI 1.13-16.6), baseline Cotrimoxazole prophylaxis given (AHR=0.27, 95%CI 0.08 - 0.87), baseline hemoglobin level <10g/dl (AHR=3.7, 95%CI 1.1 - 12.7), baseline CD4 cells <200 cells (AHR=4.86, 95%CI 1.9 - 12.7), and baseline WHO clinical disease stage III and IV (AHR=8.1, 95%CI 1.97 - 33) were found independent predictors of mortality. Conclusion: Mortality among undernourished children who were on ART was high in the first thirty-six months. Therefore, policymakers, health care providers, child’s primary caregivers, and any other concerning bodies have to pay attention to tackle risk factors in this period. Key words: Survival, Undernutrition, Children, HIV/AIDS, Antiretroviral therapy, Predictors