Background: The Guji-Gedeo conflict has gradually become the main cause of displacement in the Gedeb district, with 274,548 internally displaced persons (IDPs). Malnutrition is exacerbated in areas affected by conflict. Children affected by the conflict face an imbalanced burden of malnutrition and health problems. The purpose of the current study was to identify determinant factors associated with the nutritional status of the children (aged 6 to 59 months) who returned to the Gedeb District after being internally displaced in Guji-Gedio.Methodology: A cross-sectional study involving 6-59 months aged children who returned to the Gedeb district after being internally displaced in Guji-Gedio was conducted from December 2020- to February 2020. A bayesian binary logistic parametric regression model was applied to model the effects of selected demographic, socioeconomic, health, and environmental factors. An inference was made using the Markov chain Monte Carlo (MCMC) approach.Results: Malnutrition was found to be prevalent in Gedeb district at 45.9 percent. The covariates such as sex: female (OR: 1.358, CI : 0.584, 3.158), birth Interval: less than 24 month (OR: 3.73, CI: 0.6, 22.9), 24 – 47(OR: 2.12, CI: 0.34, 13.263), birth order: 4 – 5(OR: 0.802, CI: 0.19, 3.338), 6 and above (OR: 1.9, CI: 0.479, 7.675), mother's education level: read and write(OR: 0.490, CI: 0.072, 3.346), primary(OR: 0.266, CI: 0.043, 1.664), secondary and above(OR: 0.25, CI: 0.025, 2.45), place of residence: urban(OR:0.399, CI: 0.098, 1.631),toilet: improve(OR: 0.84, CI: 0.265, 2.66 ), mother body mass index: normal(OR:0.777, CI: 0.332, 1.81 ) and diarrhea: yes(OR: 1.2, CI: 0.218, 2.354) were the most important determinants of children nutritional status in Gedeb district. Conclusion: The overall prevalence of malnutrition in Gedeb district is about 46%. Covariates such as sex, birth interval, birth order, mother's education level, place of residence, toilet, mother's body mass index, and diarrhea were statistically related to malnutrition. Creating awareness in society related to those factors associated with child malnutrition should be further motivated. Also, to reduce childhood malnutrition, due emphasis should be given to improving the knowledge and practice of parents on appropriate young child feeding practices and frequent growth monitoring together with appropriate and timely interventions.