BACKGROUND Over the past few years, the prevalence of overweight and obesity has significantly increased among adolescents of developed countries and becoming an emerging problem in developing countries. Obesity is risk factor for diet-related non communicable diseases. These diseases are the fifth leading risks for global deaths. Virtually, all age groups are affected from consequences of obesity. The fundamental cause of overweight/obesity is an energy imbalance between calories consumed and calories expended. Globally, there has been an increased intake of energy-dense foods that are high in fat, salt and sugars but low in vitamins, minerals and other micronutrients. And decrease in physical activity due to the increasingly sedentary nature of many forms of work, changing modes of transportation, and increasing urbanization is observed. Objective: the objective of this study was to determine the prevalence and associated factors of adolescent over weight and obesity in Nifas silk Lafto Sub-City Addis Ababa. Method: institution based cross sectional descriptive study design was conducted among 385 high school students aged 10 to 19 years in Addis Ababa city from January 2017 to June 2017. To select the study participants, simple random sampling method was used. To select the study participants, the schools were first stratified by ownership as governmental and private. Three schools from government and seven schools from private were randomly selected and the number of sample size required for each school was allocated proportional to the number of students in each school and grade level. Finally 110 (28.6%) students from government and 275 (71.4%) from private were included. A structured questionnaire was used to collect sociodemographic, food intake and physical activity data. Anthropometric measurements (weight, height, age, BMI) were performed by using calibrated equipments and standardized techniques. Finally, bi variant and multi variant analysis were done using SPSS, version 20 and WHO Anthro plus software, version 1.0.4 to classify nutritional status of adolescents. iii Result: The magnitude of overweight was 36.1 % (95%CI=31.2-41) and obesity was 6.8% (95%CI=4.1- 9.4). In NifasilkLaftoSubcity, over weight and obesity was associated with sex AOR= 0.6 [95%CI=0.4 to 1.1%]. Students grade level AOR=0.4[95%CI=0.14 to 1.3%],School type AOR=1.1[95%CI=0.5-2.3%]. Way of transportation AOR=9.7 [95%CI=5.2 – 17.9%] Time spent by sitting AOR=0.09 [95%CI=0.3 - 2.7%] and Sweet food consumption AOR=0.02 [95%CI=0.004 -0.2].