Self-conscious emotions contextualized to the body's appearance are thought to motivate goal-oriented behaviours such as physical activity. More specifically, body shame and embarrassment have been associated with less physical activity, while authentic pride has been associated with more physical activity. To date, most of this evidence has been cross-sectional. Longitudinal evidence may be particularly important during adolescence, when negative emotions (e.g., shame and embarrassment) increase and positive emotions (e.g., pride) decrease while physical activity also declines. The purpose of the present study was to examine whether the body emotions of shame, embarrassment, and pride predict physical activity behaviour over time in adolescents. Participants (N = 282; 59% girls, Mage ± SD = 14.55 ± .64) in the Monitoring Activities of Teenagers to Comprehend their Habits (MATCH) study completed self-report surveys once a year for two years. Intraclass correlations demonstrated that body shame (ICC = .68), embarrassment (ICC = .66), pride (ICC = .48), and physical activity (ICC = .61) had low to moderate stability across adolescence. Linear regression demonstrated that after accounting for baseline physical activity (? = .43, p < .001), higher body embarrassment (? = -.50, p = .001) at baseline predicted less engagement in physical activity two years later. Body shame and pride were not associated with future physical activity. These findings demonstrate that body embarrassment contributes to physical activity behaviour over time, and suggest that targeting body embarrassment may be an important strategy to promote physical activity behaviour in adolescents.