Background: Childhood acute malnutrition is common in developing countries. The African region and South-East Asia have the highest prevalence of under nutrition. Ethiopia is also one of the countries in Sub-Saharan Africa with the highest rate of under-five malnutrition. Objective: To assess the prevalence of acute malnutrition and associated factors among children aged 6-59 months in Kamashi district, Benishangul Gumuz Region, Ethiopia, 2019 Methods: A community based cross-sectional study design was conducted from October 26 to December 15, 2019 at Kamashi district. A total of 814 children were included in the study. Sample size was calculated using single population proportion and online EPI INFO version 7.Multistage sampling technique was employed to select children from households. Data was collected using structured questionnaire and anthropometric measurements. Data were entered to EPI INFO version 7 and exported to SPSS version 23 for analysis. Sex, age, height and weight were entered to ENA for SMART 2011 software to convert nutritional data to Z- score of index WFH and Binary logistic regression with backward elimination technique was conducted to identify factors associated with acute malnutrition. Results: The overall prevalence of acute malnutrition in Kamashi district was 9.8 % (8.7-13.1, 95% CI) with moderate acute malnutrition accounts 5.5 % (4.5-7.9, 95 % CI) and severe acute malnutrition was 4.3 % (3.4-6.4, 95% CI).The prevalence of edema was 0.4%.Factors positively associated with acute malnutrition were children from care givers who had primary and secondary level of education (AOR=0.16 95% CI 0.06-0.41, AOR=0.21 95% CI 0.07-0.68), children who had fever in the past two weeks prior to study (AOR=4.01 95% CI 1.86-8.66), children from families who had < 5 number of children(AOR=3.63 95% CI 1.60-8.31),and children who had vaccinated according to their age (AOR=0.38 95% CI 0.18-0.82), children from mothers who had postnatal care visits (AOR=0.13 95% CI 0.06-0.30) ,children who had less than 24 months interval from the preceding birth (AOR=3.27 95% CI 1.75-6.12) were negatively associated factors. Conclusion and recommendation: The prevalence of acute malnutrition in Kamashi district was described as poor according to recommended prevalence by world health organization. So, early screening for malnutrition and nutrition surveillance activities should be strengthened. Key words: Acute malnutrition, Prevalence, Kamashi district, Ethiopia