Objectives: The purpose of this study was to examine physical activity (PA) attitudes among adolescents in Bangladesh and their associations with sociodemographic, lifestyle and activity-related factors. Study design: Cross-sectional study. Methods: A total of 781 students (52% female; mean age 14.3 years, SD 1.1) from eight secondary schools in Dhaka, Bangladesh, completed a written questionnaire. Exploratory factor analysis was used to derive positive and negative PA attitude measures. Generalized estimating equations were used to examine the associations. Results: The most frequent positive attitudes were PA would ‘get or keep me in shape’ (81%) and ‘be fun’ (73%). Common negative attitudes were PA ‘would make me hot and sweaty’ (51%) and ‘is hard work’ (42%). Multivariable analysis showed that positive PA attitudes were more likely among adolescents who had physical education classes, adolescents involved in school sports, adolescents who ate fresh fruit and vegetables daily, and adolescents who had breakfast regularly. Negative PA attitudes were more likely among girls, adolescents who slept ≤8 h/night, and adolescents who were overweight or obese; and were less common among adolescents who ate fresh fruit and vegetables daily. Conclusions: This study suggests that PA interventions for adolescents should highlight benefits for being in shape and having fun as key components of positive PA attitudes; and address negative attitudes of PA being hot and hard work. Specific strategies may be needed to address negative PA attitudes among girls, adolescents who are overweight or obese, and adolescents with insufficient sleep.