Introduction: Harmful traditional practice is form of violence which has been committed primarily against children; in certain communities and societies apart from accepted cultures.Despite lives of children and newborns after childbirth can be saved by skilled care, the main factors that prevent children from receiving skilled care during childhood are harmful traditional practices. There is limited evidence to determine the extent of children affected by harmful traditional practice in Awi zone. Objectives: the objective of study to assess the magnitude and associated factors of harmful traditional practices among under-five children in Awi zone, North West Ethiopia in 2022. Methods: Community-based mixed cross-sectional study was conducted in Awi zone on 822 women with under-five year’s old children. Systematic sampling technique was used to select study participants, who were live Awi zone. Data were entered into EPiData 3.1, exported to SPSS version 23 and analyzed. Both bivariate and multivariate logistic regressionswere used to identify associated factors. Participants in the qualitative data study were selected by purposive sampling; data was collected by interviewer guide FGD and KII. Result: The response rate was 822 (99.9%) of the total 823 women, harmful traditional practice found to be 74 %( 95% CI; 0.7092-0.7701). Mothers being urban residence (AOR=0.640, 95 CI; 0.465-0.882), Age of mothers between 15-24 years old (AOR=0.477, 95 CI; 0.253-0.900), age of mothers between25-34 years old (AOR=0.553, 95 CI; 0.350-0.872), children age being between 1-2 years old (AOR=0.684, 95 CI; 0.491-0.954) were significantly associated with harmful traditional practices. Conclusion and recommendation: The prevalence of harmful traditional practices among under-five children in Awi Zone was high. In this study we found that being rural residence, children between 3-5 years old, mothers between 35-49 years old were risk factors associated with harmful traditional practices. Thus, awareness creation targeted at improving mothers between 35-49 years old,mothers with rural settlement, and mothers with children 3-5 years old to tackle harmful traditional practices. Keywords: Magnitude, under-five years, factors, harmful traditional practice, Awi zone