Background: Adolescence is a unique period of life as it is a time of intense physical, psychosocial and cognitive development. Adolescent girls’ nutrition prior to conception is one way to break the intergenerational cycle of malnutrition. There is no study that evaluated the under nutrition among girls in the study area. Objective: The objective of the study was to determine the Prevalence of under nutrition and associated factor among adolescent girls attending high school in Rural Raya Kobo Woreda North Wollo Zone Ethiopia. Methods: Institutional based on cross-sectional study was conducted from January 4-9, 2021. This study was conducted among six high school (9-10) with a total of 3,438 Students during the time of the study of which 1,629 were females. Systematic sampling technique was used to select 323 Students. The data were collected using self-administration questionnaire. The data was checked, coded and entered to SPSS version 20 for analysis. Descriptive statistics and bivariate and multivariable logistic regression models were done to describe the data and to identify predictors of under nutrition. Odds ratios along with 95% confidence intervals were used to present the findings P - Value < 0.05 was used to declare level of statistical significance. Result: The prevalence of stunting and thinness was 18.3% and 14.6% respectively. On multivariable logistic regression model after adjusting for other variable, girls having less than 4 times meals per day (AOR=0.457.95%CI: 0.249-0.837), those having tea and coffee >3 times per week (AOR=0.327.95% CI: 0.0.143-0.837) and dietary pattern (AOR=4.961, 95%CI: 1.483-16.590) were significantly associated with stunting among the adolescent girls. Kind of food eaten at home (AOR=0.228.95% CI: 0.083-0.627), source of drinking water (AOR=0.228, 95%CI: (0.083.0.627) and starting of menstruation (AOR=0.323, 95%CI: 0.118-0.888), were significantly associated with thinness. Conclusion: The prevalence of under nutrition among adolescent girls were stunting (18.3%) and thinness (14.6%). dietary pattern, beverage like tea and coffee and feeding per day were significantly associated with stunting. Commencement of menstruation, kind of food always eaten at home, source of drinking water were significantly associated with thinness. As girls are future mothers the findings imply the need for improving the number meals girls eat especially during the time when they started menstruating and diversifying diet to prevent thinness and stunting in the study population.