This study examined the relationship between physical activity, body image, and subjective well-being among Swedish adolescents over time. Surveying 2308 students, with 137 providing longitudinal data, we conducted a multivariate logistic regression analysis. No significant correlations were found between physical activity (p = 0.268), body functioning (p = 0.567), or body appearance (p = 0.075) at age 14 and subjective well-being at age 16. Among control variables, sex (p = 0.038) and subjective well-being at age 14 (p = 0.013) showed significant correlations, while economic status did not (p = 0.39). The correlation between a positive subjective well-being at age 14 and age 16 indicates the importance of impacting the sense of well-being early. Further longitudinal studies are needed to explore the potential long-term correlation between body image and adolescent subjective well-being.