Background: Adolescence is an essential stage in the human life cycle, a transition period between childhood and adulthood. These age group are risk groups for malnutrition, but they are not part of a target in many interventions’ strategies. According to the World Bank report, academic performance of students of Sub-Saharan African countries is less than half of what is expected for their age. In Ethiopian the repetition rate in primary and secondary education is 6.9% and 8.2% respectively. Improved nutrition is believed to have the potential to positively influence students' academic performance and behavior. Therefore, this study aimed to determine the association between nutritional status and academic performance. Objective: The objective of this study was to assess academic performance and its associated factors among well-nourished and under-nourished public-school adolescents in Bahir Dar city, Northwest, Ethiopia, 2021. Methods: An institution-based comparative cross- sectional study was conducted on 976 adolescents from September 20,2021- October 20,2021 among public-school adolescents in Bahir Dar city, Northwest Ethiopia. Multistage sampling technique was used to select the study participants. Nutritional status was measured using body mass index for age using weight and height. The academic performance was measured using the mean mark score of two consecutive semesters’ results of all subjects. Structured questionnaire was used to collect the data. Data was entered into Epi-data and then analyzed by Antro plus software and SPSS software Version 23, Descriptive statistics was used to present the data, Binary logistic regression and multivariable analysis was also done. Statistical association of variables was declared at p-value < 0.05. Results: The comparison of magnitude of poor academic performance among well-nourished and under-nourished were calculated separately. The magnitude of poor academic performance was higher among under-nourished students 24%, (95% CI:19.9,27.3) than well-nourished students,12.5%, (95% CI:9.5,15.4). Having a mother who can’t read and write (AOR=4.0,95%CI:1.50,11.0), living in large family (AOR=2.0,95%CI:1.2,3.3), having scarce textbook (AOR=8.2,95%CI:5.1,14.6), poor dietary diversity score (AOR=1.9,95%CI:1.1,3.1). Using internet (AOR=1.98,95%CI:1.1,3.59) were significantly associated with poor academic performance among under-nourished adolescent students. While facing scarce textbook (AOR = 10, 95% CI: (5.6,19.4), meal skipping (AOR = 3.5, 95% CI: 1.8-7.0) were found to have significant association with poor academic performance among well-nourished adolescent students. Conclusion and Recommendation: The magnitude of poor academic performance was higher among under-nourished groups than well-nourished groups. Predictor variables, which had significant association with poor academic performance were identified. It is recommended to design interventions targeted at improving adolescents’ nutritional status which is base for academic achievement.