Negative weight-related experiences and internalized weight stigma have been associated with poorer body image and reduced physical activity in adolescents. However, exploring body image and physical activity as discrete weight stigma outcomes fails to consider the theoretically- and empirically-supported covariation between the two. The present study tested a novel integrated model of the associations among negative weight-related experiences and internalized weight stigma (via weight-related distress), body image (shame, authentic pride, body appreciation), and physical activity. Canadian adolescents (N = 311, M ± SD = 16.00 ± 1.01, 75.5% girls) completed a cross-sectional self-report survey. A structural equation model with maximum likelihood robust estimation was tested. Higher negative weight-related experiences were indirectly associated with poorer body image (i.e., higher shame; lower authentic pride and appreciation) through higher weight-related distress. Authentic pride was associated with moderate-to-vigorous physical activity. Higher negative weight-related experiences were indirectly associated with lower physical activity through higher weight-related distress and lower body-related authentic pride. These findings elucidate targetable individual mechanisms and larger systems that could improve body image and foster physical activity among adolescents who encounter negative weight-related experiences and internalized weight stigma.