BackgroundIn spite of surplus food production, in Amhara region, a significant number of children had under-nutrition. Investigating factors associated with under-nutrition in food secured households is crucial to design preventive measures. Therefore, the objective of this study was to assess under-nutrition and associated factors among 6–59 months old children in food secured households in Western Amhara Region, Ethiopia.MethodsA community-based cross-sectional study was performed using interviewer-administered questionnaire on 6–59 months old children from Jun 01–30/ 2017. A multi-stage sampling strategy was used to select study participants. Prevalence of stunting, underweight, wasting and overweight/obesity were computed. Predictors were assessed using logistic regression analysis.ResultThe prevalence of stunting, underweight, wasting and overweight/obesity were 40%, 19.8%, 11.6%, and 2.7%, respectively. Having mother who have no formal education (AOR] =2.21, 95% CI: [1.5, 3.2]), taking less diversified food (AOR =1.7, 95% CI: [1.1, 2.5]), having mother who did not wash her hands before food preparation (AOR =1.46, 95% CI: [1.1, 2.0]) and living in the households where solid wastes managed by scattering in the field (AOR =1.6, 95% CI: [1.1, 2.1]) were predictors of stunting. Whereas, wasting was associated with having illness in the prior two weeks of data collection day (AOR =2.7, 95% CI: [1.6, 4.7]), lack of getting antenatal care (AOR =2.0, 95% CI: [1.1, 3.4]) and taking food less than four times per day (AOR =2.00, 95% CI: [1.2, 3.2]).ConclusionThe prevalence of under-nutrition was very high. Therefore, health professionals and health extension workers should give nutrition counseling about the frequency and diversity of meal, environmental and personal hygiene by giving emphasis to mothers who have no formal education.Electronic supplementary materialThe online version of this article (10.1186/s12887-018-1386-2) contains supplementary material, which is available to authorized users.